Howdy Katrina!
Thank you so much for your question! Two and four are such great ages for a Walt Disney World vacation! At those ages we spent, and still to this day spend a good part of our time at Fantasyland at Magic Kingdom. You'll be spending quite a bit of time there, and will likely do a good bit of re-visits to attractions. Some of our kids' favorites are Peter Pan's Flight, it's a small world, The Many Adventures of Winnie the Pooh, Prince Charming Regal Carrousel, Dumbo the Flying Elephant, Under the Sea ~ Journey of The Little Mermaid...all great favorites of ours!
At Disney's Animal Kingdom, my kids love Kilimanjaro Safaris, as well as Pangani Forest Exploration Trail and
Maharajah Jungle Trek. The fruit bats that you'll encounter on Maharajah Jungle Trek are amazing, and so wonderful for the kids to see up close! Another area you'll want to check out while at Disney's Animal Kingdom is Conservation Station, and don't miss Finding Nemo - The Musical! Our kids also love watching the birds in Flights of Wonder.
I hope you have a magical vacation, and thank you so much for stopping by!
Amanda