If Edith Wharton hadn't become one of the 20th century's great novelists, she would have made a fine decorator. The woman who wrote The House of Mirth once likened a person's nature to "a great house full of rooms," and delighted in building and decorating her own "great house"—a 13-room mansion in the Berkshires called the Mount. Beginning June 4, Wharton's fabled home celebrates its centennial with a tribute by today's leading designers, among them Bunny Williams, Thomas Jayne, and Lady Henrietta Spencer-Churchill. Because Wharton's original furnishings were long ago sold at auction, the designers will each do a room as if Wharton were their client today. What would the author have made of these efforts?"She was a very forward-thinking woman," says the New York—based Jayne. "I'm not trying to make just another pretty French room. I think Wharton would have outgrown that." The Mount, 2 Plunkett St., Lenox, Mass.; 413/637-1899.