I recommend going to wdwinfo.com and checking out the menu's if you haven't already! We haven't had all that many sit-down meals, and we also don't have any kids, but here are our favorites:
Ohana - Breakfast with Lilo, Stitch, Mickey, and Pluto.
The food is great and it's never ending!! You can refill as many times as you want! I've also heard that they have a great dinner menu.
Crystal Palace is really nice too. It's a buffet style and the food is really good although if you go for the character meals, it tends to feel crowded. There is not a lot of space between tables and with the characters and servers all trying to walk through it can get cramped.
The Plaza Restaurant in MK has fantastic sandwiches. I'm drooling just thinking about it!
We ate at Liberty Tree Tavern in October and while it wasn't awful, it wasn't our favorite. The character interaction was the best of the character meals that we have been to, but the food was just average.
If you and your family like seafood, Coral Reef in Epcot is great! Eating next to a giant aquarium is a very cool experience!
The Rainforest Cafe is good too but we like the one in AK better than the one in DTD. We had much better service at the AK location and much better food.
Speaking of DTD, we also really like Planet Hollywood. A lot of people will bash it but we have never had anything even remotely close to a bad experience.
If you like Mexican, San Angel Inn in the Mexico Pavilion is fantastic. Again, it's kind of cramped as there are a lot of tables in a little bit of space, but the food is soooo worth it!
I don't know what it's current status is, but Nine Dragons is another one of our favorites. Again, a lot of people bash it for whatever reason but again, we've never had a bad experience.
Boma at the AKL has great breakfast! It's a bit of a pain to get to if you're using Disney Transportation and you aren't staying at AKL because you have to take a Disney bus to a park and then transfer to another bus to take you back to the lodge. As long you allow plenty of time to get there, it won't be an issue or if you are coming from a park already and going there for dinner you won't have any problems.