When my son was 12-13, he'd have happily spent all day, every day in DisneyQuest. I could never stand that place and left him to it while I shopped. He was thrilled with that arrangement as he has never enjoyed standing around while I shopped, anyway. I think it's in the male genes or something.
I haven't been in there in years and don't know what it's like these days. I wouldn't take kids younger than 8-10, though.
Water parks - depends on if you like them. The slides are fun, but if you don't get to them early, you can wait forever on busy days to ride them. Lazy rivers are nice...not as relaxing as you'd imagined, perhaps, but pleasant. If I arrive at a water park for opening, I usually leave around four or five. They really are a lot of fun, IMO.
Bring your Coppertone Sport! It is, IMO, the best sunblock for the water parks. Apply it in the morning and, just for the hell of it, re-apply after a few hours of riding slides and hanging out in pools and stuff! So many people get terrible burns at the water parks! Really bad burns. And that stuff WORKS.
Have fun!