Leah,
We took our kids 3 and 7 in December. If it is warm when you visit your 3 1/2 will have much more to do! We happened to hit some very warm weather and this is what he was able to do.
Toon Lagoon
Me ship the olive
Jurassic Park
Jurassic Park discovery center
Triceratops encounter
Jurassic Park River Adventure (make sure you tell your child it is not real)and still the dinosaur at the end is frightning
Pteranodon Flyers ( he hates this and was very frightened) I hated this since I could not comfort him as we were in seperate seats.
Camp Jurassic ( He LOVED this whole area)
The Lost Continent
The Mystic Fountain ( one of his favorites)
The flying unicorn ( he enjoyed this ride)
Marvel superhero island
Spiderman ( was scared the first time, yet asked to ride it again the second day, 4 more times)
They have a parade daily around 3-4P with all the superheros (he loved this!)
Seuss Landing
He loved everything here. we spent a great amount of time at this island.
They also have a character lunch from 12-2P daily at Confisco's. We found this to be terrific and he still talks about it.
All kids are different. If you are unsure do the ride yourself first. The colors and theming of this park alone were simply amazing.