I have not had good luck with DD restaurants, with one exception. House of Blues was overpriced and the food was mediocre. Definintely avoid Planet Hollywood, way overpriced, too loud, bad service and boring food. However, we thoroughly enjoyed Portobello Yacht Club. The food was very good, the wine was very good, and the service was excellent. It is somewhat expensive, but a good value for the quality of food and service.
At the resorts, some of my favorites are:
1) California Grill (absolute hands-down favorite) at Contemporary
2) Yachtsman Steakhouse at YC
3) Beaches and Cream at BC
4) Olivia's at OKW
5) BOMA at AKL
6) Whispering Canyon at WL
Character Meals:
1) Breakfastosaurus in AK
2) Chef Mickey's at Contemporary
In the parks:
1) Crystal Palace (when they reopen)
2) Counter service across from tomorrowland speedway with Sonny the lounge singer (cannot remember the name)
3) The Land pavilion counter service at EPCOT
4) Pizza Planet counter service at MGM
5) Backlot counter service at MGM
Like the other posters said, it all depends on what you like. As you can see, we like a variety of types of places and are also very casual. No way is it a vacation if I have to dress up to eat!!