Hello, Cathy!
It sounds like you are planning a magical day for your little princess and her brothers. Cinderella's Royal Table and a visit to the Bibbidi Bobbidi Boutique are two of the most sought-after princess experiences at the Walt Disney World Resort, and it's so exciting that you were able to make reservations for both on your upcoming trip.
Both of the dining locations that you mentioned offer delicious foods, gorgeous dining halls and interactions with several lovely Disney Princesses, but there's something so special about dining inside of the iconic Cinderella Castle. Personally, I would keep the reservation at Cinderella's Royal Table and save Akershus Royal Banquet Hall for another time, as it is usually more difficult to secure a dining reservation at Cinderella's Royal Table for any time of day.
Another thing to take into consideration is the types of foods served at each dining location. You may find that one restaurant offers foods that are more appealing to your family's tastes, so I highly recommend taking a moment to look over the current online menus for both
Cinderella's Royal Table and
Akershus Royal Banquet Hall.
I hope that you and your family have a magical Walt Disney World vacation, Cathy! If you have any other questions about dining with the Disney Princesses, I hope that you will stop back by the Moms Panel. Happy planning!