My son, who is now a teen, was about that old on his first trip to WDW.
We ate at a three signature restaurants. He still remembers the Brown Derby where he had chicken noodle soup with Mickey pasta and a hot dog.
We also ate at the Yachtsman where he remembers the dessert, a white chocolate puzzle you could put together, they also had 3 favors of topping you could paint on, chocolate, strawberry and I think butterscotch.
The last was the California Grill, he still talks about the view during dinner and watching wishes from the roof of the Contemporary. In fact he picks the California Grill to eat at every trip since the first.
I hope this helps.