Are the Doctor Who novels considered canon? Do they tie into the storylines, or are they one-off adventures/monster-of-the-week stories?
I'm asking specifically about the New Series Adventures, featuring the 9th, 10th, and 11th Doctors.
That is actually two different questions, I think, with different answers:
Are They Canon?
As Micah points out, Doctor Who famously has no canon, as everyone involved in producing the show has very notably avoided ever making any statements about what is or isn't canonical. The closest I think we have is Russel Davies once mentioning that they didn't worry too much about what happened in the books when they wrote the episodes.. but then again, most Doctor Who writers barely worried about what happened last season on television when they wrote episodes, so that's not a big change.
The status in the RTD era can basically be summed up as: "This show has almost no internal consistency anyway, on top of which, The Time War, so there.)
Do They Tie In With The Storylines?
Yes, but very little. This is actually something new to the NSA books; in the previous novels like the Virgin New Adventures there was, to my knowledge, never any references made to plots from the novel written into any future episodes. This may be partly because the novels often continued with a Doctor's incarnation well past the end of his televised run.
In the NSA, there is carryover from the televised product into the novels: a lot of the 9th Doctor's novels included the whole "Bad Wolf" plotline as part of them. Also, there was at least one case where a NSA plot was referenced, though offhandedly, in a television episode. (The Doctor mentions a trip to the Justicia system, which happened in a novel.)
Mostly, however, the NSA novels cover things that happened "in between" the television programs. They will roughly follow the basic plot of the show -- they will, for example, change companions in the novels around the time they change companions on TV -- but they are, for the most part, stand-alone.
I think the most answerable question is how the New Series Adventures and other books fit into the Doctor Who stories - the novels are independent of the television storylines, save that they may feature the same characters and/or races as the television series. All of the ones I've come across fit the one-off adventure/monster of the week description (though that doesn't preclude a story arc occurring that I'm yet to encounter).
As to whether or not they are canon, I think the essay Micah linked to gives a good summary. Specifically, there has been no indication that the books are canon, with one exception:
The closest we ever got to a BBC pronouncement on canonicity was a couple of years after the end of the original series of Doctor Who. The show’s last production team declared that Virgin’s Doctor Who novels, the New Adventures, were an official continuation of the series, overseen by the last producer, John Nathan-Turner, with the last writing team onboard, heading towards the aims that that team had put in place.
The Doctor Who landscape this was announced in has since changed significantly, as Virgin lost the rights to Doctor Who novels and the reboot has occurred.
Overall I think the best summary is that the books can be considered canon unless the television series contradicts them.
The BBC oversaw Virgin's New Adventures and considered them TV Tie-in, meaning they fit within the established story set by the TV series. Same goes for the Missing Adventures, the Past Doctor Adventures, New Series Adventures and the Telos novellas. TV sets the stage, the books flesh it out. Remember, key phrase "TV Tie-in".
There is no Doctor Who canon and never could there be. Yes, there is official Doctor Who and there is Doctor Who continuity. Not all Doctor Who fits in to the main continuity of the series. Many of the BBC's Eighth Doctor Adventures deliberately took place in alternate universes like in Blue Angel. Sometimes the series deliberately wrote itself out of the time line like Alien Bodies to The Ancestor Cell and beyond, all taking place in a paradox ridden and some say aborted time line. Neat trick. Some eras of Doctor Who didn't take place in our universe, so no effect was mane in the time line, like the Doctor Who Big Finish 8th Doctor main range. Then there are Short Trips and Side Steps. Again, real life Doctor Who, but set in alternative universes, or take adventures on a different path than that of the established history of the Doctor. The comics of the Seventh Doctor often took place in alternative story lines as well. But they were all official Doctor Who.
A TV adventure is forty five minutes now. That's like 50 to 60 pages of script? The audios have the freedom to go further with a story tan 45 minutes. The novels have practically no bounds. 300 pages some of these stories. In depth ad jam packed at times. Just consider the Wilderness Years to be a time when Doctor Who glaciered out. It was a time when Doctor Who could do anything. but the New Adventures were the continuing stories of the Seventh Doctor's life. No doubts. Probably the best series of DW novels ever written.
I'd have thought that anything Doctor Who broadcast by the BBC is canonical, with a slight grey-area over BBC Radio (where a number of Big Finish audio plays have been broadcast). Of course, that would make Dimensions in Time canonical!
There is no established canon for Doctor Who. Doctor Who canon is this: There is no canon. If the BBC say it's official Doctor Who, then it is 100% bonafied Doctor Who. TV show takes precedence, but the novels and audios are official.
The BBC has never said there is a Doctor Who canon. The TV show is publicly owned by the British people, bless them, and it's a rule that the TV show be self contained because one has to buy a book, or buy an audio adventure. The rights belong to the BBC but the medium changes the economics. Even with this stipulation, nothing says other mediums "don't count". That's silly.
If it still boggles the mind to include such a vast rich history of our hero, just remember the TV show gives you every thing you need, but that in no way, diminishes the history outside the television medium.
Sorry. That's just not true. Doctor Who DOES have a canon. it has always had a canon. BBC Law dictates that ALL original BBC Drama Series have self-contained continuities. The viewer must "get the whole story" from JUST watching the tv show. Anything that the television viewer could not get from watching the tv show is not canon, nor will it ever be.
It is interesting that people keep linking to Paul Cornell's BLOG when discussing this. First off, it's a BLOG, not an official pronouncement from the BBC. Second, it's riddled with factual errors. One such error is that the Virgin New Adventures were "the official continuation of the series overseen by the last production team". It is well-known that John Nathan Turner had nothing to do with these books. It is less well-known however that the series wasn't actually cancelled in 1989, simply rested. Thus the show as set to continue ITSELF.
As far as "official", bs. BBC Drama (or presently BBC Wales) makes the tv show "Doctor Who". BBC Worldwide (which has nothing whatsoever to do with the tv show) licenses out the copyrights of the show to outside businesses who then produce merchandise. This merchandise has nothing at all to do with the Production Office. This merchandise includes action figures, posters, puzzles, books etc. Every producer in Doctor Who history has stated that they have nothing to do with this merchandising, and people like Letts, Turner and Davies have publicly stated that they don't even read etc. most of it.
What is interesting is that all the people who scream the loudest that "There is no canon!" are people like Cornell, Orman etc. In other words the people who write all these novels. They KNOW what they are producing is licensed merchandise that is no more canon than a pair of TARDIS boxer shorts, but they won't admit it. So they post factually inaccurate blogs about how "Canon doesn't exist" and about how the books "were the official continuation".
Let me just state this clearly: NOTHING that isn't part of the tv show is canon. Kate Orman will cry from the rooftops that there's "no such thing as canon", thereby convincing herself (and sadly others) that her books are equal to the tv works of Davies, Holmes or Dicks. Prior to actually writing for the show, Cornell would not shut up about how "there is no canon". But there IS a canon. it's the TV show. Kate Orman has NEVER written for Doctor Who. What she has done is write licensed merchandise using Doctor Who copyrights. The fact that certain books (e.g. Human Nature by the aforementioned Cornell) and audios (e.g. Jubilee) have been adapted for the tv show shows that they aren't canon. RTD also totally ignored things like the Torchwood audios, because they aren't canon.
The next time someone smugly declares "there is no such thing as canon in Doctor Who" or "the books/comics/audios/whatever are every bit as real as the television show" take a closer look at WHO is saying it, and WHY they are saying it. Most likely they're someone who has written loads of this merchandise, and are trying to elevate it to the same status as the TV show. Cornell's infamous blog was written before he wrote for the TV show. What he had done up to that point was a lot of books, audios etc. None of it was canon. Bernice Summerfield does not exist in the Doctor Who canon.
The policy is even cited Cornell in his anti-canon BLOG. There is an online PDF at the BBC's website explaining their policy. What people forget is that the BBC is NOT a business corporation like ITV or CBS or FOX. It is a publicly-funded public service, that is monitored and controlled by the British Government. Attempting to equate Moffat(or any other BBC-employed Producer) with Lucas or Whedon or Roddenberry is a mistake. It's chalk and cheese. BBC Programmes are funded by the UK Public's tax money and Licence Fees. All BBC employees are essentially civil servants working to provide the Public with a service(in this case Entertainment). Yes, that DOES sound silly, but that was the way the BBC was since before World War II, and the basic structure has never changed, although it's far more slickly-run today. BBC Enterprises(now BBC Worldwide) was set up as the BBC's commercial arm, originally to sell BBC shows to other countries(thereby making more money to pump back into the BBC). Soon, they branched out, and realised that they could sell the rights to other companies to produce merchandise using BBC copyrights. The money the BBC made from these licensing deals could likewise then be put back into the BBC. But, it's MERCHANDISE. It's unrelated to the Doctor Who continuity/canon/whatever you want to call it itself.
Yes, this is long and "rambling". But there are SO MANY errors in the usual "there is no canon! The producers have never stated a canon position!" bs lie. Again, Paul "No Future" Cornell has shouted tha "there is no canon position!" because he has written so many of these books. Did you ever hear Robert Holmes say "there is no canon"? Barry Letts stated publicly that the Production Team had nothing at all to do with the spin-offs like books, comics etc. RTD totally ignored things like the Torchwood audios, and publicly stated that the 'Looms' don't exist in canon.
The problems are:a)the people who make this spin-offery will obviously want it to be "just as real" and that's why the Virgin authors will never miss an opportunity to say how "there's no such thing as canon" b)anyone(including me) who has spent a LOT of money on spin-offery doesn't like the ''idea'' that they've spent money(and subsequently time) on something that "doesn't really exist". But like it or not that's how it is.
The bottom line which people miss is this:Doctor Who itself doesn't need its own canon policy. In fact, if it tried to define its own canon policy, it would literally be illegal. That's because all original BBC Television Drama has the exact same canon policy. Again Doctor Who is a BBC copyright, and is funded by BBC tax pounds. The Doctor Who production Office is NOT an independent company like Lucasfilm. It is a department of BBC Drama. The producer is a salaried BBC employee, NOT some Lucas-type maverick. Whatever canon policy the BBC dictates, Doctor Who follows. It is not the place for even Russell T. Davies or Steven Moffat, let alone a hired writer like Paul Cornell, to state what the policy is. You don't ask the guy who works the drive-through window about McDonald's Corporate Policy, do you?