Hi Linda!
Wow, you will have so much fun with 5 kids under 12 and I do recommend calling daily to see if any reservations open up for Cinderella's Royal Table. If you're asking specifically about Advanced Dining Reservations, I can recommend the following:
Cinderella's Happily Ever After Dinner; although characters are always subject to change, typically you'll find Cinderella, Prince Charming, Lady Tremaine and the wicked Stepsisters, offering plenty of entertainment for all ages of your children; located at Disney's Grand Floridian Resort & Spa
Boma - Flavors of Africa; I'm a huge fan of visiting the beautiful savanna at Disney's Animal Kingdom Lodge and the kids will have the opportunity to view the animals while waiting for your table or perusing the Resort Hotel. Boma won't disappoint as there are so many wonderful family-friendly options on the African-inspired buffet.
Hoop-Dee-Doo Musical Revue; A dinner show is a fantastic way to end an evening, especially at Disney's Fort Wilderness Resort! Many families make this dinner show a must-do on their trips.
You'll want to be sure to call 407-WDW-DINE, 407-939-3463, or book online to reserve any table service or dinner show option.
For a non-dining suggestion to make your trip most magical, consider booking Pirate or Mermaid transformations at The Pirates League in Magic Kingdom. For more information, call 407-WDW-CREW.
I'd be happy to offer any other specific suggestions, so feel free to visit me again.
Have a MAGICAL vacation!
Sherri