Impulse speed (for a starship) is between 0.25c and 0.8c (maximum speeds of course) and usually restricted to sublight.
Warp drive is a bit more trickier, but it was established that the technical manuals are not canon.
Still, even if Warp 9 = 3000 times LS (for example), in Voyager, it was established on screen that Warp 9.9 = 21 473 times LS.
Now, if in TNG Warp 9.9 = 3000 times LS, that could simply mean that the Warp scale might have been re-calibrated (again) and 9.9 now ended up at 4 billion miles per second.
At any rate, Warp factors and speeds fluctuate wildly in canon.
I usually stick with the on-screen dialogue however and use higher values as the technology and science in Trek certainly should allow for them.
So, Warp 9.9 = 21 473 times LS.
But I think that doubling of speed with every incremental increase is valid for Warp speeds above 9.9 (meaning that 9.91 = 42946 times LS, etc.)
Of course, past Warp 9, speeds start increasing quite fast anyway.
So, if Warp 9 (or 9.2) = 1500 times LS and 9.9 = 21 473 times LS, then we have several decimals of large increases to work with.
Warp 10 was stated to be in Voyager 'infinite velocity'.
Anywhere in between you can have a large range of speeds that can be achieved through say more efficient/powerful Warp drive (recalibrated Warp scale in TNG final episode where they said Warp 13, etc), Slisptream, Transwarp and Coaxial warp drive (to name a few).
Slisptream v1 seemed to have equaled 300 ly's per hour at maximum from on-screen dialogue.
For protracted periods of time though, it was suggested the crew of Voyager would need to be in Slipstream for 3 months (which in itself suggests the ship would have needed to go much slower for extended periods of time to allow crew survival - or it was possible the engines on the Dauntless couldn't sustain maximum velocity for long periods of time).
Slisptream V2 as developed by Voyager crew (who used a number of technologies) in 'Timeless' seemed to have allowed speeds of 10 000 ly's per minute (and if you check the dialogue, it says that the slisptream variance doesn't appear until about 17 seconds into the flight... which doesn't leave much time for Voyager to experience issues and crash into its doom or for future Kim to send the needed data back in time to help disperse the Slipstream).
This version of Slipstream even seemed to surpass Borg Transwarp capabilities (at least until the Dauntless and Arturis were assimilated by the Borg, which could have lead to the Collective to improve their TW drives by the end of Voyager series).
Anyway... There are also Soliton Waves which traveled at below Warp 9 (though showed evidence they can increase in speeds), but the thing is that ships using soliton wave technology wouldn't need actual Warp engines (further research into this technology might have yielded SF with better mobile control that didn't require another station at the end to disperse the wave, but could otherwise be done on the go via a ship using the waves to traverse space).
Borg Transwarp through use of TW coils for independent TW conduit generation seemed quite fast... it allowed the Delta Flyer to traverse 200 Ly's in a few seconds (10, maybe 20 seconds?).
We know that when Voyager equipped its engines with 1 Borg TW coil, they traversed 20 000 ly's... although, they didn't say how long it took them to do that... it could be about 33 or 34 minutes (if the above assessment of 200 ly's per 20 seconds is accurate).