Hi Susan,
You have several options to dine with Cinderella. My favorite princess meal is
Cinderella's Royal Table inside Cinderella Castle. Your granddaughter will see her downstairs and then will get to visit with other Disney Princesses while dining.
You can also try
Cinderella's Happily-Ever-After Dinner which is located inside the Grand Floridian. Here you'll see Cinderella, Prince Charming, Lady Tremaine and often the step-sisters as well.
Currently Rapunzel does not attend character meals. However, she is available for Meet & Greet opportunities inside the Magic Kingdom. See this link
HERE for details.
The character dining is extremely popular, so you'll want to book it as soon as possible, up to 180 days in advance. Cinderella's Royal Table in particular really fills up quickly. You can call 407-WDW-DINE (at 7:00am, 180 days out) or you can book online
HERE (at 6:00am 180 days out).
Have a magical vacation with your family and please let us know if we can assist you further,
Kaylene