Crystal Palace is a good choice. With little kids, I always think the buffets, which spend the least time waiting for your food and have easy access to the characters, are the best. Play 'n Dine @ Hollywood and Vine has playhouse Disney characters JoJo and Goliath and Leo and June from Little Einstein's, which my DD liked a lot when she was three (Note that there are no characters there for dinner), and we are going back to again this year. Another good choice is one of the Mickey-centric buffets if your older DD is into Mickey Mouse Clubhouse...Chef Mickey's, Garden Grille, Liberty Tree Tavern (dinner only), or Donald's Breakfastsaurus (is it still called that?) at AK all work.
As far as non-character meals - Coral Reef @ Epcot has the giant fish tank, which may fascinate your child. The buffet at Beirgarten in Germany @ Epcot was surprisingly good and they have an oom-pah band as well.
Note if you go to Cinderella's Royal Table...Dinner does not have princesses other than Cinderella in the lobby, only the fairy godmother and giant mice at the dinner...I recommend breakfast or lunch...for that kind of money, I should get princesses..dangit!
SkierPete