Toothsome and their super sized desserts should be a hit with the kids - I haven't eaten there yet but the consensus always seems to be that the service is on the slow side, so I'd probably make a dinner reservation rather than try to do lunch.
Cowfish is fantastic for dinner, with many kid friendly options.
These days, I'd recommend a reservation for any sit-down restaurants you want to try.
The Harry Potter restaurants are quick service / counter service - you can just walk in. The theming is fantastic if you're an HP fan. Everyone flocks to the HP restaurants for lunch, so if you don't like lines you can try to eat at off-peak times. I've also heard good things about the revamped menu at Thunder Falls Terrace in Jurassic Park. If you like tater tots, there are the cult favorite smothered tots at Green Eggs & Ham in Seussland.
The Universal website catches a lot of flak for some reason, but I think it's great for narrowing down restaurant choices - basically every restaurant and quick service location has their menu listed so you can see if it appeals to your family's palate. We made a short list for places we'd like to eat, and for quick service lunches and snacks we plan to hit up whatever on the list sounds best at the time or is closest. It's an approach that works for us.