...I would take your 4 year old to Seaworld. The only thing his height will allow him to do is Seuss Landing in IOA and the Nick Studios in Universal. There's a cool Barney show at Universal also, but you'll have to decide if you want to spend the money on just a few things between two parks. I could be missing a couple of things, but as I remember, my 7 year old neice missed height requirements on about 4 rides. SHE WAS NOT HAPPY!!
Go to Seaworld and give your 4 year old about 3 more years so he or she can really enjoy the Studios.
Dreams Unlimited Travel is committed to providing you with the very best vacation planning experience possible. Our Vacation Planners are experts and will share their honest advice to help you have a magical vacation.