In the United States, the Greek restaurant seems like a very localized phenomenon. Here in the Cleveland metropolitan area, diners and "family style" restaurants owned by Greek-Americans are very rare. A few hours drive to the northeast, in Buffalo, you'll find Greek restaurants everywhere, even though there really isn't a large Greek population.
Most Greek restaurants in Buffalo aren't very ethnic; they're not the kind of places that serve whole lamb, or where you smash dishes and scream "OPA!" They might have a few Greek and Mediterranean/Middle Eastern dishes -- souvlaki, gyros and the like -- but for the most part they're family-style restaurants serving meat-and-three comfort food. Many are open 24 hours. In Buffalo, you don't impress a date by taking her to a Greek restaurant; it's like having a date at Denny's. (The Towne, though, in Buffalo's Allentown neighborhood, is considered a pick-up spot among that neighborhood's large "alternative lifestyle" population.)
There's a lot of Greek restaurants in New Jersey, I've been told. I'm wondering ... are there other parts of the United States, or other countries (excepting Greece of course) where Greek restaurants are common? What form do they take there? Is there a large Greek population in those areas?