I went to T-Rex Cafe with my 3 year old nephew earlier this year, and he loved the atmosphere. It is chain like food, but the 4 of us all enjoyed our food, and our server was pretty good. Rainforest Cafe is also popular among kids, and the theming is well done but their menu isn't as extensive and the food isn't as good as T-Rex, IMO.
Raglan Road is one of my favorite places at DTD. The food is good, although the wait can be ridiculous even with a reservation, and the entertainment at night is fun.
I would stay away from Crossroads at the House of Blues (one of the worst dining experiences of my life and definitely the worst at Disney) and Planet Hollywood was an overpriced disappointment as well.