Hi Webwoman, don't want to put you off but I have to say we didn't have a particularly good time. My opinion of Atlantis was that it was a theme park (a very expensive one) with beds.
Don't get me wrong, the hotel looks amazing but in my opinion it is just too big and really lacks in customer service. Having been so excited about going we were really disappointed. I suppose that it is good that we did go but we feel it didn't live up to its expectations. We have travelled extensively in the Middle and Far East and have stayed in much nicer places.
I have to say it does look amazing and everything is all very clean and sparkly, it is just the customer service that really lets it down and I think its because it is so big. Another really annoying thing were the huge groups of tourists that pay to go and look round it. One day it was very hard to get back in the hotel and back to our room from the beach as there were hundreds of tourists following their guides around (holding huge wooden numbers on sticks) and it felt like being in a cattle market.
Food and drink is VERY expensive, around 5 to 6 pounds for a latte I think is taking the P*. I took lots of cartons of juice and long life milk for my youngest two and lots of cereal bars and snacks otherswise we'd have spent a lot more. We bumped into friends of ours there and they also felt the customer service was lacking so it wasn't just us.
I think if you are realistic about it (and the total cost) you may enjoy it and I'm sure your DC would love the waterpark. DD1 (14) absolutely loved it, particularly the fact that Peter Andre was there and she got her photo taken with him!
We have stayed at the Jumeirah Beach hotel a few times and next time we go back we will almost certainly stay there again.
There was a thread a month or so ago (where to go in February half term) and other people had visited Atlantis and gave a few reviews so maybe have a read and see what they thought.
Hope you have a lovely time wherever you go