If you are looking for TS and want to stay in the park, we enjoy Liberty Tree Tavern for both lunch and dinner. As previous posters mentioned, lunch is an ala carte menu and dinner is a fixed price thanksgiving-type meal. We have a couple picky eaters in our family of 5, and everyone is always happy with Liberty Tree.
If you are looking for TS and are willing to leave the park, I highly recommend either Kona and Ohana at the Polynesian. I like the atmosphere at Ohana better, and we enjoy the bread, salads, appetizers and desserts (not so much the meats lately.) It's all-you-can-eat and fixed price. If you're looking for great Disney theming and lots of food, Ohana is a good choice. Kona is a reasonably priced alternative next door with an ala carte menu - lots of great items on that menu.
If you're looking for TS, are willing to leave the park and would consider a signature restaurant, then California Grill is one of our favorites for food, atmosphere and view.
If you are looking for CS, Columbia Harbor House of El Pirata. The menu at CHH is fine and I think the atmosphere is the least hectic of the MK CS options. If it's open, we really like El Pirata - relatively fresh Mexican food with a great toppings bar. But it's seasonal, so it's hard to say whether it will be open at any given time.