Le Cellier is excellent, I also like Chef de France and Nine Dragons in Epcot. Yachtman is excellent too, but if you are on the dining plan this requires 2 sit downs and Le Cellier only one.
MGM it's 50's Prime Time, Brown Derby and even Sci-Fi, I don't like Mama Melrose.
MK - Kona Cafe was very good for dinner, quiet and right on/off the monorail. And whoever mentioned Concourse Steakhouse is right, everyone seems to forget about that place and I've always heard good things about it and plan to try it next trip. The Grand Floridian Cafe for dinner is good too and Crystal Palace.