Why do the Weasleys go to Egypt twice in the same year?

Question

During Christmas in Harry's second year Mr and Mrs Weasley embark on a cross-continental trip to visit Bill in Egypt.

Harry found it peaceful, rather than gloomy, and enjoyed the fact that he, Hermione and the Weasleys had the run of Gryffindor Tower, which meant they could play Exploding Snap loudly without bothering anyone, and practice dueling in private. Fred, George and Ginny had chosen to stay at school rather than visit Bill in Egypt with Mr and Mrs Weasley.
_{(Chamber of Secrets, Chapter 12, The Polyjuice Potion).}

Yet, the following summer, they and their children are back in Egypt again, less than a year after their previous trip.

MINISTRY OF MAGIC EMPLOYEE SCOOPS GRAND PRIZE
Arthur Weasley, Head of the Misuse of Muggle Artefacts Office at the Ministry of Magic, has won the annual Daily Prophet Grand Prize Galleon Draw.
A delighted Mr Weasley told the Daily Prophet, "We will be spending the gold on a summer holiday in Egypt, where our eldest son, Bill, works as a curse breaker for Gringotts Wizarding Bank."
The Weasley family will be spending a month in Egypt, returning for the start of the new year at Hogwarts, which five of the Weasley children currently attend.
_{(Prisoner of Azkaban, Chapter 1, Owl Post).}

We know that:

• The Weasleys may have cared more about a quality family experience than money.
• However, visiting Egypt was a costly trip. The Weasleys could only afford to go in PoA after getting the Daily Prophet windfall. It's presented as a 'once-in-a-lifetime' trip.
• The second trip must have been quite dull for Mr and Mrs Weasley, having visited only a few months ago.
• Bill is not the only Weasley child living abroad. Charlie also lives away from home, working with dragons. If Mr and Mrs Weasley want to visit their children because they don't see them enough, why would they visit Bill twice and ignore Charlie?

So why go back to Egypt?

Answer 1

They visited Charlie for Christmas in the year before that (Harry's first year):

It was true that Harry wasn't going back to Privet Drive for Christmas. Professor McGonagall had come around the week before, making a list of students who would be staying for the holidays, and Harry had signed up at once. He didn't feel sorry for himself at all; this would probably be the best Christmas he'd ever had. Ron and his brothers were staying, too, because Mr. and Mrs. Weasley were going to Romania to visit Charlie.
(Harry Potter and the Philosopher's Stone, Chapter 12)

So it was one Christmas with Charlie and one with Bill.

The third trip was something like a gift for the whole family - Charlie was also there:

Harry scanned the moving photograph, and a grin spread across his face as he saw all nine of the Weasleys waving furiously at him, standing in front of a large pyramid. Plump little Mrs. Weasley; tail, balding Mr. Weasley; six sons; and one daughter, all (though the black-and-white picture didn't show it) with flaming-red hair. Right in the middle of the picture was Ron, tall and gangling, with his pet rat, Scabbers, on his shoulder and his arm around his little sister, Ginny.
(Harry Potter and the Prisoner of Azkaban, Chapter 1)

Why choose Egypt over Romania? Maybe it is a personal preference. They were in both places and decided that there is more to show to their children in Egypt.

Also, I guess in Romania Charlie was in some wild region, far away from tourist attractions, while Bill was working around ancient places (the Pyramids etc.) where there are curses to break.

Answer 2

Keep in mind as well, that though the Weasleys were fairly poor, the actual traveling in the Wizarding World may not be as expensive as in ours for just the parents (perhaps via Apparition, or Floo Powder, or even an authorized Portkey). Most of the cost would presumably come from time spent in the country.

Therefore, it's not unreasonable to believe that Mr. and Mrs. Weasley traveled as often as they could, to keep in touch with their dear sons.