Martha Stewart is an expert on home cooking, but she went to the Four Seasons for Thanksgiving. She was spotted with Barbara Walters, Casey Ribicoff, real-estate broker Dolly Lenz, Marvin Hamlisch, David and Helen Gurley Brown, and Margo and Jimmy Nederlander. Martha and her daughter, Alexis, later did snifters of Hennessy Cognac Paradis with Julian Niccolini, the eatery’s co-owner, who was crowing on Black Friday that they’d served 900 dinners on Thanksgiving Day. “We are sold out for Christmas Eve!” he bragged. Doesn’t anyone stay home on the holidays?