As others have mentioned, Plaza Restaurant is on the right as you walk down the end of Main Street as you walk towards the Tomorrowland Noodle Station.
Its small, but not cramped and decor is similar to the Crystal Palace with the late 19th century theme. I've only seen the Main Street Characters show up once, but they were funny and interacted with everyone before moving on offstage.
We had never been there ourselves until 2008, but its probably our favorite table service in MK now. Sandwiches are excellent with quality ingredients and they are large enough that you'll want to split them so there's room for dessert. The desserts are great as well so try to save room.
If you're looking for something different and a slower paced lunch, I'd recommend making some reservations, I'm sure you'll enjoy it.