Hi Cheryl!
Cinderella always greets you as you enter Cinderella Castle for
Cinderella's Royal Table. As for the other princesses, I have seen Belle, Jasmine, Aurora and Snow White, but these are always subject to change. For a fabulous character dining experience with the boss himself, my favorite is
Chef Mickey's at Disney's Contemporary Resort. There you can have an American buffet Breakfast or Dinner and have great photo opportunities with Mickey, Minnie, Goofy, Donald and Pluto.
I have done the "last minute" reservations by calling every morning, at about 7AM Florida time, to see if anyone has cancelled their reservation. You should also check other character dining experiences, such as
Ohana's Best Friends Breakfast with Lilo & Stitch at Disney's Polynesian Resort,
Donald's Safari Breakfast at Disney's Animal Kingdom or
Playhouse Disney's Play n' Dine at Hollywood and Vine at Disney's Hollywood Studios. But I must admit that I haven't been successful getting character dining reservations on every last minute trip we've planned.
Have a magical vacation!