No! Cinderella greets everyone downstairs (atleast for breakfast that is what happens) so you will definately see Cinderella but the princesses upstairs are apparently random.
Cinderella always there for formal pictures in the lobby. That is part of the package so she has to be there!
But I do not believe you will see any other princesses upstairs during dinner. It will be a "celebration" song that the Fairy Godmother sings and Susie and Pearla (sorry I am probably spelling their names wrong!!!) the mice flit very quickly around the room. Breakfast and Lunch are different than the dinner.
Dinner has more menu options than lunch. I think it's geared a little more for older children and adults. I had dinner at CRT during my last visit and enjoyed it very much.