We went to CRT last Sept and ended up having to search for most of the princesses the rest of our stay. We had gone to the PSB at Norway the year before and saw all the princesses there except Cinderella. My daughter's fav is Ariel, so it was a real treat for her to see her in her dress vs her tail!!
Of course characters are "subject to change", but I think if you want to see the most princesses go to PSB. However, dining in CRT is also nice just for being in the CASTLE, but expect to see at most 2 princesses if lucky 3, with Godmother, Mary Poppins or Alice filling the gaps.
Remember-- dinner at CRT is Cindy downstairs, with Godmother and Mice in dining room. No chance of other princesses for CRT dinner.
Have you considered doing BBB for her? She would love it- I did crown package for my little one and she just loved it!! Have a great time and hope your little girl has a GREAT Birthday!!