Hi Anne,
The California Grill isn't actually in Magic Kingdom, it's a restaurant in the Contemporary Resort which is one of the monorail hotels overlooking the Magic Kingdom. It is a beautiful place to watch the Magic Kingdom fireworks Wishes from as is the beach there!
There are 3 Princess dining locations in Walt Disney World, the most popular is Cinderella's Royal Table in Magic Kingdom. The characters that tend to be there are Cinderella, Belle, Jasmine, Snow White and The Fairy Godmother. It is a beautiful meal inside the Castle but is also the most expensive and the hardest to get a reservation for!
You can also find the Princesses at Akershus Royal Banquet Hall in Epcot, the Princesses are similar to CRT. Breakfast is pretty standard food but traditional Norwegian food is served there at lunch and dinner.
Lastly there is 1900 Park Fare at the Grand Floridian, this is the only meal with a Prince in attendance and is a yummy buffet. Normally present are Cinderella, Prince Charming, Lady Tremaine and the Step-sisters who are just hilarious. This is the one I would recommend for your party and the meal I think the boys in your group would enjoy the most.
You can find details on all these restaurants at the main
www.disneyworld.com site, some even include menus. Which ever you choose though make sure to phone and book your dining reservations on 407-939-3464 as soon as you are 90 days before your arrival date, especially with a party of 12.
I hope you have a fantastic trip,
Jo