I've been to WDW 6 times in the last 5 years. With a little kid, I have to say, that the best dining experiences are Crystal Palace (Magic Kingdom), the Tuskerr House with its new character lunchtime dining (Animal Kingdom), and Chef Mickey's (Contemporary). My family is partial to pacific culture, and we love that the Polynesian has two really neat restaurants, O'Hana and the Spirit of Aloha luau.
Like everyone has said, make reservations as soon as you can.
Cinderella's Royal Table is a great experience for your little princess, but like Larry said, the food is rather miserable. I don't know if it's coincidence or not, but the two times we've eaten there, we've had bad adult experiences with random parents who were extremely aggressive. I suspect it's because it's such a popular and expensive place.
For adults, nothing beats dining at Epcot's World Showcase. Our best meals have been at La Hacienda de San Angel, Tokyo Dining, and Le Cellier, in that order. Our most fun meal is *by far* at the Biergarten. Marrakesh was pretty good. Haven't tried Nine Dragons. There is character dining at Akserhus in Norway. France and Italy were woefully bad, especially Italy.