'Ohanas has Mickey, Chip, Dale, and Goofy for sure. Sometimes Minnie has been there but I don't think you can count on it. They only serve a character breakfast at 'Ohanas. For dinner here, there are no characters but they do some great interactive games for the kids and it's very much a family atmosphere.
Chef Mickey's serves breakfast and dinner.
I second the idea that it sure is nice when touring the parks all day to have someone wait on YOU! Although I'm sure you are Supermom and able to take care of all those young ones, I guarantee you won't mind sitting back and letting someone else help you care for them for a change.
The Garden Grill is a revolving restaurant at EPCOT that has Mickey, Pluto, Chip, and Dale. They serve breakfast, lunch, and dinner. You sit in a booth and the server brings things to your table family style. Characters give great interaction here.
almost every/any place you go will help make the meal more festive if you let them know ahead of time you are celebrating a birthday. When you make your priority seatings have it noted, and then remind them when you check in for your meal.
Sending lots of pixie dust your way!
Brenda