If you can do both parks, there is enough in the two parks to fill a day for the kids. Suess Landing in IOA has four rides for little ones plus a play area and is very well themed. There are also a few other play areas in IOA for them to be entertained. Then go over to USF and ride Jimmy Neutron, Shrek, perhaps Twister depending on the kids and Jaws depending on the kids. Do the whole Curious George area and Barney show and Animal show. Ride ET and if your girls are brave you can do the Horror Makeup Show. That should fill a day very nicely.