1) Garden Grill at Epcot's Future World has a very healthy lunch including salad stuff and veggies grown there in the pavilion, and it's a rotating restaurant so you get a cool view of The Land too.
2) Crystal Palace in Magic Kingdom is a big, sunny and bright place with a great reputation for character interaction and it's open all day, so pretty flexible.
3) Donald's Breakfastosaurus in Animal Kingdom is the only place to meet Donald at a character meal and it has cool "dig site" decor - nice place for a late breakfast.
Liberty Tree Tavern at MK is a close runner-up. I've also heard great things about Chef Mickey's, 1900 Park Fare and breakfast at Ohana.