Hi there, Yvette!
Each of the four Parks at Walt Disney World comes offers rides, attractions, and entertainment for all ages. But with children as young as yours. I would definitely focus on the Magic Kingdom.
Fantasyland is geared toward the little ones. Head there first thing! Don't Miss: Prince Charming Regal Carrousel: “it's a small world”: Dumbo the Flying Elephant in Storybook Circus; The Many Adventures of Winnie the Pooh; Walt Disney World Railroad (kids enjoy watching it pull in and out of the station even more than they like riding it); and The Magic Carpets of Aladdin ride in Adventureland.
Epcot is great for wandering, too. Turtle Talk with Crush is a fun interactive experience; make sure also to see Figment in the Imagination Pavilion, and ride a Clammobile in the Finding Nemo ride (please note that each of these does have a bit of darkness).
Disney's Hollywood Studios is home to Disney Junior: Live On Stage, a great interactive show starring their TV favorites, including Jake and the Neverland Pirates, Handy Manny, and of course, Mickey Mouse. With the exception of Toy Story Midway Mania (which will be great for the three-year-old), the ride selection here is geared toward an older crowd, but there is enough to see and do that you can make it at least a day's fun.
Finally, Animal Kingdom has a great playground just for the little ones. And don't miss the Kilimanjaro Safari, where kids can get up close with animals on the sprawling savanna.
More suggestions can be found on
Disney's official Web site.
Have a wonderful trip!
See you later, celebrator,
-Deborah B.