Minnie's is our favorite character meal. We like to do the rope drop - power walk through the FL rides and a few others and then go rest at Minnies for brunch. We've found that later in the morning it tends to be more relaxed and less crowded and that we can spend a ton of time with the characters. We love being able to relax at an outdoor terrace table and enjoy that wonderful and happy DL atmosphere!
Anyway, we've been several times and the cast has varied slightly. Minnie and all the Pooh characters (Pooh, Tigger, Rabbit, Eeyore) have been there every time. And then we've also seen:
Captain Hook
Chip and Dale
Mad Hatter
Fairy Godmother
There were probably more but those are the ones I remember off hand.