MK: Tomorrowland - Buzz, Indy speedway (if you don't mind the whiplash if you let drive

), TTA, astro orbiter is a bit fast I think for little kids
Toontown - Donald's boat, the little playground, probably too small for Goofy's Barnstormer
Fantasyland - everything here is good except maybe Snow White - that one's a little scary
Liberty Square - probably bored on Hall of Presidents, and HM is too scary, but he can ride the paddleboat
Tom Sawyer's Island - everything
Adventureland - Swiss Family tree, Jungle Cruise, POTC maybe, Alladin's Magic Carpet, Tiki Room
Epcot:
Future World: Mission Space has a great toddler play area in the exit area
Journey into Imagination is great for toddlers and the play section after the ride is fun
Living with the Land, Living Seas, Spaceship Earth
World Showcase: have him do masks, El Rio del Tiempo is fun
MGM: Great movie ride (except the Aliens segment), Playhouse Disney, Voyage of the little mermaid, backlot tour, lights motor action, fantasmic, beauty & the beast, indy jones stunt show, muppetvision
AK: Triceratops spin, Kilimanjaro Safari, he can go on Kali if he's 36inches or more, all the shows he can go on.
That's the ones I can think of.