WIth a 3yo, I'm all for Sea World. It's a fun place, educational and the shows are fun for all ages. Just don't sit in the "Splash Zones". Each show has it's own number of rows as the splash zone. THey have taught the killer wales to really toss the water a long ways now, so the entire lower section has the possibility of getting wet. SW also has a "pet show" with dogs, cats, geese, other birds, a pig. It is a great show.
Favorites at SW Orlando:
Clyde and Seamore Sea Lion and Otter show
The "pet show"
Killer Whales
Dolphin show
Downtown Disney is also a good place to visit. You can browse through many shops (the Biggest
Disney Store in the WORLD too).
Or heck, go to the Magic Kingdom for the day. You can't do everything so don't try. Enjoy Fantasyland and Mickeys Toontown, ride the train around the park, go on Buzz Lightyear, watch the parade, jungle cruise, country bears, tom sawer island to run around on, the river boat, aladdin's flying camels, the main street vehicles, Swiss family tree house, tiki birds. That sounds like a pretty full day that's not overloaded.
A lot of kids enjoy the monorail around the lagoon or take the one over to Epcot and back.
Have fun.