Hello, Christy,
You are going to have such a special evening with your grandchildren! Since you already have reservations at Chef Mickey's, would you like another opportunity to dine with characters? At the Grand Floridian Resort, guests can enjoy dining with Cinderella, Prince Charming, and some of their friends at
Cinderella's Happily Ever After Dinner at 1900 Park Fare. Just a note that this is a buffet, so that may be more work for you.
Another enjoyable restaurant is '
Ohana at the Polynesian Resort. With 'Ohana meaning family, this restaurant serves meals family style and invites children to race with brooms and coconuts, dance to island music, and try their skills at hula-hoops. If you time it right, there are tables where guests can see the fireworks from the Magic Kingdom, too. You also have the option to dine and then go down to the beach of the resort to watch the fireworks and Electrical Water Pageant.
At Disney's Contemporary Resort, there is another restaurant called
The Wave, which focuses on serving healthful food choices. Another aspect I like about this restaurant is that it has a calmer feel than the buffet and character meals, which makes for a nice change of pace.
I hope this helps to give you some ideas. If you'd like more information or have more questions, I'm happy to help. Have a magical trip!