At the Magic Kingdom:
Crystal Palace - all three meals have Pooh, Tigger, Eeyore and Piglet. This is buffet style. I've been to breakfast and dinner here, and while the dinner is good, the breakfast offerings are to-die-for
Cinderella's Royal Table - Also has characters at all three meals. Typically has all Disney princesses. The food is ordered off a set menu, and when you arrive at Cinderella Castle for your reservation, a photographer will be on hand to take pictures of your group in the lobby, before you are seated. This meal takes 2 dining credits, and is nearly impossible to get ADRs for. Try as early in advance as you can.
The Garden Grill - Chip and Dale's Harvest Feast, dining only
Princess Storybook Dining Breakfast at Akershus Royal Banquet Hall in the Norway Pavilion
At Disney's Hollywood Studios
Playhouse Disney's Play 'N Dine at Hollywood & Vine- has characters from the morning Disney shows
At Animal Kingdom
Tusker House - Has Donald, Daisy, Goofy, and Mickey with "African inspired" breakfast food
Cape May Cafe - . Goofy, Minnie, and Donald are there for a breakfast buffet. The food is really, really good - this is the husband's favorite place to eat at Disney!
Chef Mickey's - Contemporary
1900 Park Fare - Grand Floridian. Breakfast has Mary Poppins and dinner has Cinderella
Polynesian -- 'Ohana Character Breakfast - every morning with Lilo and Stitch, Pluto and Mickey
Have you tried a character meal? Which is your favorite?