Lucky Dog Cafe [attn: fallingwater]
Location: Confluence, PA
Open: Till 9pm all days of the week (Seasonal, closes in winter.)
Clientele: There's a bike trail out back, also some hikers and a lot of locals. (Translation: you don't need to dress up)
Atmosphere: Homey, with a wooden "log cabin/hunting lodge" aethetic, airy and kinda coffeehouse like. Outdoor seating may include dogs.
Mains: Local, grassfed beef -- the burgers are outstanding! (Don't bother putting fancy toppings on, it simply distracts from the beefy goodness)
Sides: They make their own fries here, and their own chips too, look to be using Russets from the flavor. They are excellent fries and chips, definitely worth ordering.
Drinks: Good selection, both alcoholic and non.
I'd say its well worth the 15 miles or so from Fallingwater or Ohiopyle. Besides, it's beautiful country and a wonderful drive.
[This is a capsule review. It's what happens when people kvetch about not getting enough reviews on the board. It's easy, you too can write one.]