Colleen:
First, don't give up on a Character Dining experience. Put the Disney Dining number in your cell phone (407-939-3463) and dial up whenever you think about it! Cancellations happen every day.
In the meantime, I'd recommend either
Biergarten, Teppan Edo, or Coral Reef at Epcot. Biergarten's oompah band invites all the children to join in the Chicken Dance....now THAT'S a picture. Teppan Edo's chefs prepare dinner before your eyes transforming onions into trains and spell-binding even the youngest in the group. Coral Reef sports an aquarium expanding the length of the restaurant--ask for a seat nearby. Talk about captivating!
As for the Magic Kingdom, don't rule out the resorts nearby via the monorail like 1900 Park Fare at the Grand Floridian with Cinderella, Prince Charming and the Wicked Stepsisters in attendance. California Grill at the Contemporary offers a viewing deck of the Magic Kingdom--and the fireworks. No doubt memorable for not only your child but you as well!
Wishing y'all a magical vacation!
Whitney