I'd go with T-Rex. You can go to Rainforest Café in various places throughout the country. There are only 2 T-Rex restaurants, one in DTD and the other in Kansas City. We went last November and found the service to be exceptional. Server was attentive, managers checked on our dining experience, etc. All without being annoying about it. If you join the Landry's Select Club, you get a welcome reward that offsets the cost of joining. This also puts you at the top of the waitlist when checking in. I was unable to get a reservation in advance, so we went anyway, I put my name in at the booth, and we were probably seated 5 minutes later with a party of 5. Food was decent.
However, I was surprised that my 3.5 year old son did not enjoy the experience. He likes dinosaurs and the theming in the restaurant is quite fun, but it terrified him. And this was a child who was brave enough to go on the Tower of Terror multiple times on the trip (he is very tall for his age). He actually said, "I want to get out of here." It was quite surprising. So I'd suggest maybe walking a small child into the restaurant first to make sure they are okay with it, or not wheeling them in while asleep in the stroller and having them waking up to load sounds of dinosaurs. That was probably our mistake. But the baby enjoyed it!