I have been to both several times, and when I ask my 6 and 4 year old what is their favorite park in Disney they both say Seaworld!! We had such a great time the last time we went! I suggest taking it slow, and doing whatever you can. There is no race to get it all done, if you don't there will be something left for your next trip. (My favorites are the dolphin show, feeding the dolphins, which is extra $, but so worth it, and touching the mantarees)
I also love Disney Studios, but it is a little harder to get around w/little ones, and I also felt like it was more hot. It did not feel like there was a lot of shade and the kids were a little irritated from the heat. However, they have the playhouse Disney show and the little Mermaid, the Muppets and a couple of good restaurants as well. As an adult, Disney Studios is my favorite. But thinking as a child, I would still have to say Seaworld.
Whatever you choose, have a great time. They are both wonderful, and much better than a day at work!