I am taking my 21 month old this weekend. There is a lot for them to enjoy as tippytoe said. At US, we had a great character interaction in front of I Love Lucy . They had Chucky, Tommy, Dora, Anglica. They were all very attentive to my DS last August. He was 15 months old then. The store next to the Jimmy Neutron ride has a fun area to run around and you can meet Spongebob there. Lot's of fun at Barney show and Fieval. Let your little one watch the Nick Jr channel and he'll get a feel for the characters and should be able to recognize them.
Over at IOA they also have Camp Jurassic where you can walk around and explore. Good place to TRY and tire the kids out. Also at toon Lagoon the good ship Olive (name?) and lot's of fun scenery to interact with.
Their child swap are the best. I believe all the major rides have it. Just ask a CM for directions.
TabbTIgger