Founding Farmers has what’s very likely the best brunch menu in town (brunch is available Saturdays and Sundays from 9am-2pm). They have a location right in Tysons close to the DoubleTree and the Hilton Garden Inn. Reservations highly recommended. Their lunch and dinner menus are also good.
For a delicious and adventurous brunch menu, we recommend heading over to Ambar in Clarendon (Arlington). They serve small tapas-style plates from Balkan cuisine.