I recommend staying at any of the deluxe resorts becasue they offer more activities for the young ones. For example at the Contemerary Resort, they have music and arts and crafts at the pool as well as a character meal in the Tower called Chef Mickey. You wont Be disappointed with that choice.
Out of the four parks I recommend the Magic Kingdom because they have many attractions for kids to enjoy. Some rides in Fantasyland your kids would enjoy are Its a Small World, Peter Pans Flight, Dumbo the Flying Elephant, Snow Whites Scary Adventures, Cinderellas Caroussel, The Tea Cups, and The many adventures of Winnie the Pooh. S far as other theme lands, they might enjoy Mickeys Toontown Fair, which is a town to meet Mickey and the gang. You can even go inside of some of there homes. If You have a boy he would enjoy Buzzlight year Space Ranger Spin. If your kids are dare devils take a stroll over to the Mountains, that include Space Mountain__ Tommorland, Thunder Mountain and Splash Mountain__Frontierland. If you and your kids want a chance to see many of the disney characters I recommend the Disney Dreams Come True Parade which starts at 3:00pm every day. They might even enjoy Spectro Magic, another parade at 9:00pm. Even though Ive given you alot of information dont miss the other parks they still have a couple of rides for the young ones, like Voyage of the Little Mermaid and Playhouse Disney:Hollywood Studios, Nemo:Epcot, and Kilamonjaros Safaris:Animal Kingdom