If you're looking for characters, Cape May Cafe has an excellent breakfast bufftet and it's much calmer than CM's. Crystal Palace is good (a little crazy but good) and has Pooh Bear & friends.
If you just want a really good breakfast buffet, try Boma's. It's fantastic!
'Ohana and Cape May have character breakfasts outside the parks. If you're looking for Mickey, I think he may be at Ohana with Lilo and Stitch, but apparently he isn't at Cape May.
In the parks there is Tusker House (Mickey should be there along with Donald and others) and Crystal Palace (Pooh characters)
Our favorite breakfast (character) our last trip was Ohana. It has Lilo, Stitch, Mickey and Pluto. Great food, great atmosphere. The kids get to march around the restaurant with the characters shaking marraca's. It was just a very nice meal, not over the top at all. And we loved that it was served family style. Lots of fruit and the works.
Sorry you can't get Chef Mickey's - we love it! I would suggest Crystal Palace - we like it almost as much as Chef Mickey's. Very good buffet: nice selection and unlike CM's they have puffed french toast which is excellent. Crystal Palace also has a nice, fun atmosphere - during our meal there last year, Tigger led a parade of kids around the restaurant.