It is difficult to imagine any man-made attraction in this country that is, at once, more than 200 years old, still growing by leaps and bounds and still welcoming guests every day in the grandest style. Such is the case at the Greenbrier Resort, a National Historic Landmark in White Sulphur Springs, W.Va. Even the jaded traveler must agree with Lynn Swann, Greenbrier’s director of public relations, when she says confidently, “We are just a four-hour drive away from a place [Washingtonians] won’t find anywhere else in the world.”