Sophie:
You've got me between a rock and a hard place on the recommendations....to be honest, the best table service restaurants for young children are usually the Character Meals. However, these restaurants usually offer a buffet and are more expensive than ordering from the child's menu at other table-service restaurants. The good news is that your daughter will be eating for FREE! (Another way to save money at a table service restaurant is to go at lunch instead of dinner--most restaurants offer a similar menu!)
On with the recommendations!
Epcot: Le Cellier offers a respite from the park not to mention a thick, juicy steak. You can order a la carte and the children's desserts are memory-makers!
Disney Studios: Sci-Fi Dinner Theatre puts you in the middle of a drive-in movie--complete with a car for a table! If you're ordering from a menu it's a better buy than eating here on the dining plan.
Animal Kingdom: Rainforest Cafe surrounds you with animals the children will just love! The children's menu sports the usual fare, but again, for the money, the entertainment is more affordable than the Character Meal at Tusker's House.
Magic Kingdom: Crystal Palace: This is the one restaurant I would splurge on the buffet. Pooh and friends greet all the diners, but the lunch buffet is one of the least expensive yet expansive outside Biergarten in Germany at Epcot. The extensive dessert bar and ice cream machine make eating a fun experience, too.
If you'd like to look at more prices and compare more menus, I recommend taking a peak at
www.allears.net under Dining!
Wishing you a magical vacation!
Whitney