My son was almost 2 when we went las year.
Hands down his favoirtes were the toddler playground areas! In MK there's Pooh's Thoughful spot (by Pooh ride), Donalds Boat & Mickey's Playard (Toon Town) and even a small one by the ext if Splash Mountain. In AK he loved the play yard in Dinoland and there's Honey I Shrunk Kids play yard in DHS.
As far as rides attractions - he went on following:
MK: Peter Pan, It's A Small World, Pooh, Carousel, Tea Cups, Indy Race Car (Daddy drove and he got a Indy License from the CM when we got off!), Buzz Lightyear (He really didn't play the game but he liked looking at Buzz), Aladdin's Carpet, Jungle Cruise, Country Bear, Tiki Room
AK: Safari, Triceratop Spin (Dinoland - like Dumbo only you ride in a dinosaur), He didn't last long in the Flights of Wonder show - he spent alot fo time in the play yard here. I think Rafikis planet will also be good - it has a petting zoon and all - we didn't get to it, but plan to this year.
DHS: Playhouse Disney show was the big attraction here - he enjoyed the parade and we had some great charater meets here with Soccerer Mickey and Cars. We also did Toy Story Mania - again he didn't play but enjoyed watching everything that was going on.
EPCOT: Didn't spend much time here - we did Nemo and he saw Illuminations. We watend to do Journey to Imagination but it closes at 7pm and we were there after 7. This year I want to walk around the world showcase with him.
He enjoyed the parades in MK and DHS. He had fun at the character meals we went to as well as meeting characters.
He didn't have the patience to wait for and sit thru shows so we didn't do many of those. This year I think we'll be able to do some.
Obviously we spent the most time in MK, but there's plenty for them to enjoy throuhout all the parks.
Have Fun