Depending on how late the parks are open, you could do both parks, we spent one whole day in each easily, but they closed at 7pm. If you choose to do both, make sure you arrive before park opening-have been told they open 15-20 minutes before stated opening time. Have tixs already purchased beforehand. Get maps of both parks and study them so you don't waste time.
For the ages of your kids I would recommend-
IOA:Spiderman, Hulk(if he is tall enough, and still wants to ride after actually seeing it) , Dueling Dragons(same thing). Bilge-rat barges,Ripsaw Falls, Jurassic Park River Adventure. Poseidon's Fury if you have time, read the reviews on this forum in regards to it being dark
US:Mummy,Men in Black, Earthquake,Jaws, Horror Make up show, Jimmy Nuetron, Shrek 4D, Twister. Back to the Future I would only do if you have expresspass, not worth a long wait, very bumpy simulator. Curious George playground has a cool two level ball area behind the water town where you can shoot balls with air cannon, pick them up with vacumn, a cage that drops a bucket of balls every 4 minutes.All my kids 11,7,3, had a great time here, but I would do only if you had more time.
Bring a change of clothes with you-there's many rides where you will get drenched!
Also, you may want to make a PS for a restaurant in Citywalk for lunch. You'll be passing through that area to get to the other park or if time is of the essence, just do a quick counter lunch and have dinner at citywalk after the parks close.