I would second the Whispering Canyon recommendation, kids will love it!
Also O'Hana's at the Polynesian is fun with Lilo and Stitch and they have coconut races and other things for the kids.
Crystal Palace at MK is a fun buffet and I thought the character interaction was fabulous with Winnie the Pooh and friends.
The Coral Reef at Epcot has the huge aquarium which is neat and will give them something interesting to look at for a while.
At MGM the Sci-Fi Restaurant is cool, you get to sit in 'cars' and watch old sci-fi clips, although i've heard the food isn't so great. But i'm sure if you stick with burgers and shakes it will be fine!
Boma is a great buffet at the Animal Kingdom Lodge...after lunch the kids could get to see all the animals on the Savannah at the Lodge, its really very beautiful!
The Garden Grill at Epcot (The Land Pavilion) is a rotating restaurant that overlooks scenes from Living with the Land and has characters as well, that could be entertaining!
For more expensive options you have Mickey's Hoop Dee Doo Musical Revue at Fort Wilderness or the Luau at the Polynesian.
If you're not on the dining plan the Rainforest Cafe is a lot of fun for kids too, lots to see and do although it can be a bit dark inside.
Finally, although I haven't been, I hear Chef Mickey's is fabulous and fun and has great character interaction!
Let us know what you choose in the end! Isn't it fun booking restaurants?!
