Yes, there's . . .
At USO:
Shrek 4D
Jimmy Neutron
ET
Curious George play area (could get wet here)
Animal Planet Live
Barney
Woody Woodpecker Kidszone
Maybe the Jaws ride (if it's re-opened)
At IOA:
Suess Landing (several rides & Cat-in-the-Hat is great)
Jurassic Park area has several interactive areas including the
climb-and-explore Camp Jurassic and the Camp Jurassic Discovery Center
Toon Lagoon (kids especially will like Popeye's Me Ship. The Olive
which they can climb all over)' and the stretch where there are lots of
cartoon figure exhibits and some character interactions.
In both parks there may be some other rides they would like, depending on how bold/adventurous your kids are (especially if they've already had their appetites whetted by some of the kid-specific rides).
USO/IOA doesn't have the "Disney Magic" imho, mainly because of fewer character encounters and the lack of rides/shows with a "fairy tale" atmosphere. USO/IOA does have more thrill rides that will appeal to teens and adults, but that's not what you said you were looking for. If you have young children, you're probably not wanting to do marathon opening-to-close days and I think you would have plenty to keep the three year-olds entertained.