A friendly word of warning:
If you want Cinderella's breakfast, be prepared to call as soon as the Dining Reservation lines are open, to do so exactly 60 days in advance of your intended dining day, and then pray.
I called a few weeks back and got thru at 7:01am Eastern and they were sold out. And it was exactly 60 days before our intended dining day.
Fortunately, we were warned numerous times about how hard it is to get in for this breakfast. As a result, our party of 10 had three phones going. Of the three, one and only one got the reservation. The other two, myself included, were told at 7:01 and 7:02 respectively that they were already booked full--not the thing I wanted to hear being half asleep at 4:00am pacific time.
I was bold enough to ask if this instant selling out routine was common and the CM said that it was--that they can be completely booked off of their first calls answered every morning. It's a numbers game--40 operator CMs answering to book only a set number of seatings. Apparently, the restaurant isn't so large.
If you like face characters (meaning ones without a mask who actually talk to the kids) or you have girls who want to meet Disney movie babes, then 1900 Park Faire came highly recommended by the CMs as a nice back-up plan. It's in the Grand Floridian which is right next to MK. The consolation is that it's Alice, Mary Poppins and Mad Hatter.
Also don't forget Breakfastasaurus at AK. They, too, do a Character Breakfast, but there are no characters present at this eatery for lunch or dinner. I also thought that the Polynesian Resort does a Minnie-related character breakfast at Ohanas, but I'm not sure if they are still doing this one after 9/11 cutbacks.