IOA is for small children too. There's more at IOA for them than there is at US. While my DD certainly enjoyed US at 3 1/2 she had more fun at IOA and preferred IOA again at 4 1/2
IOA
Seuss Landing
Caro-Seuss-El
One fish 2 fish
Cat in the Hat
If I ran the Zoo
Toon Lagoon
Me ship the Olive
Comic Strip Lane
Jurassic Park
Triceratops Encounter
Visitor's Center
Pteranodon Flyers (? depends on the kid, you sit one behind the other, not side by side, 36in)
Camp Jurassic (great play area)
Lost continent
Flying Unicorn (36 in)
Psedon's Adventure (sp?) can be scary, depends on the kid
The talking fountain
The Eighth Voyage of Sinbad (can be loud, but usually ok for small kids if you sit in the back)
Universal Studios
E.T. Adventure
American Tail: Fievels Playland
JAWS (scared my DD at 2 1/2, but she liked the now gone Kongfrontation)
A Day in the Park with Barney
Animal Planet live
Nickelodeon Studios Tour
Twister (dark and loud, depends on the kid)
Woody woodpecker coaster (36 in)
Curious George Goes to Town