At that age, my girls loved loved loved the Jungle Cruise, Aladin's carpets, Haunted Mansion (??), Pirates of the Caribbean, Small World, Peter Pan, Pooh's Adventure, Dumbo, the carousel...all the usuall suspects in MK.
Epcot was a little slow for us, but they've always loved The Land and Spaceship Earth. There is one ride about energy and has Figment, the little purple dragon. That ride will later mean therapy for our daugthers. It's very very loud and at the end the whole set breaks out with a huge burst of air. It scared the crap out of our older daugther!!! We'll never go on it again. And for some reason, Illuminations at Epcot scared them. They both hated the fire.
In AK, they loved the Kilamanjaro Safari and the Tricertop Twirl. They also loved the train ride to Conservation Station.
In DHS they liked the Playhouse Disney show. Everything else was a little intimidating. The movies were loud and the live shows with animatronics freaked them out. But they loved the Beauty and the Beast stage show.
We definitely spent the majority of our time in MK. Oh and they loved the Baby Care Centers. They had toys and boy girls really enjoyed the opportunity to just chill out for a little bit.
Have a great time!