We have 3 kids (now 7,6,and 2) who are Disney veterans by now! At Epcot, they love the fountains, Journey to imagination, Wonders of Life activities, and the Illuminations fireworks at night (best show in town!) At MK, best non-ride options for small ones are tiki birds and country bears shows, the shows in front of the castle, and Toontown. (Note -- Donald's boat is closed right now for refurbishment). In AK, kids enjoyed the Lion King. (We went to flights of wonder and Pocahontas, but kids couldn't seem to focus on it ... didn't move fast enough, or was too far away, or something...) And in MGM, oh my, this is THE PARK for shows! Playhouse Disney, The Little Mermaid, Muppet 3D (Again, tho', Beauty and Beast was too distant, like a play, to hold a young tot's attention). They liked the action stuff too, like Backlot tours and Indiana Jones, provided your small ones aren't scared of "kabooms" and the sight of fire.
ONE NOTE: We avoid LIKE THE PLAGUE the "playgounds" with our small ones (specifically, Honey I shrunk the kids). Personally, those playgounds have been a nightmare for us. The nooks and crannies are all kid accessible, but once your kid goes in 'em, you can't see them or find them! There is no age disntinction -- it was sheer pandemonium of everything from toddlers to pre-teens, running, pushing, shoving, pouring down slides, hanging from the rope nets... It appeared many had no parent watching them (I think the parents were in the eating area and had sent kids "off to play" while the adults ate/ rested). Parents that were there were, like us, either wedged in some cave trying to fish out a tyke or hollering our children's names blindly into the air in a desperate attenpt to keep an eye on them. Totally out of control. I did notice on our trip a week ago that Disney did at least put an "ages 4 and up" sign on the playground. That alone says it all -- we aren't the only parents who found it a safety hazard for the small set!
Cindy