There are only a handful of restaurants around the world where two customers can spend close to $100 for lunch and leave feeling not so much well fed as grateful for having been allowed in. Of these, New York's "21" is, arguably, preeminent. Its high, wrought-iron gates, the black limousines parked at the curb and the intimidating doormen give "21" the aura of a private club. Inside, amid fraying upholstery, oak paneling and original Remington paintings, the captains of politics, industry, broadcasting and entertainment dine shoulder to shoulder with the likes of Jackie O, Henry Kissinger, Elizabeth Taylor and Frank Sinatra. Johnny Carson met his third wife, Joanna, in the main dining room, and Ernest Hemingway was a regular patron whose apocryphal account of seducing a gangster's girlfriend in the kitchen has become part of the restaurant's lore. The three connected brownstones at 21 West 52nd Street have catered to New York's elite for more than half a century.

Now Sheldon J. Tannen, president of the "21" Management Company, is making it a little more egalitarian: He is exporting "21" to the capital-intensive cities of the Sun Belt as a kind of rich man's Holiday Inn. In Dallas "21" already operates a restaurant-hotel called the Mansion on Turtle Creek, and has plans to manage another in Houston next year. These two new establishments, both financed by a daughter of the late oilman H.L. Hunt, could double the $10 million income the New York "21" brings in annually. And Tannen, 57, is looking ahead to a small but glittering chain of hotel-restaurants already planned by the Hunt grandchildren: "My hope is that within 10 years, '21' will have projects in every major American city with the right social and economic mix."

Since the Dallas restaurant opened in August 1980, the Mansion on Turtle Creek has been the place to see and be seen. Its recently restored peach-colored stucco walls and red roof tiles form an eclectic mix of Mediterranean styles. The atmosphere, however, is 52nd Street. "The Mansion has the same '21' magic that attracts," explains Dallas socialite Annette Strauss. "You know if you go there, you're going to see your friends. You feel like you're someplace."

Since there's no place precisely like "21," none of the new operations will bear its name. "The connection with '21' will be low-key," says Tannen, "because we cater to people who don't have to be impressed." Still, menus at the Mansion have the "21" logo and offer such "21" house specialties as mushrooms à la Daum and chicken hash Mornay. Even the telephone number has 21s in it, and boxes of "21" chocolate mints are left at the bedsides of overnight guests. The new restaurants will also feature the "21" style of service: smothering patrons, at least the important ones, with attention. All "21" employees from the headwaiter to the receptionist keep up with society news and are sensitive to seating celebrities at a comfortable distance from ex-spouses and former paramours. To preserve the customers' privacy, Tannen does not allow photographers into "21" except for private affairs although reporters are permitted—as long as they don't eavesdrop on the guests.

Though Tannen's Texas prices are a cut below 52nd Street ($9.50 for a Dallas hamburger compared to $14.50 in New York), dinner for two at the Mansion often runs upwards of $100. Yet some potential customers go elsewhere for a different reason. "There are celebrities who don't like what we stand for," Tannen concedes. "You know, a lot of people don't want to be fawned over."

"21" has been fawning over its clientele since January 1930, when Jack Kriendler and Charlie Berns opened a restaurant-speakeasy originally known as "Jack and Charlie's." Their descendants still run the business. Tannen, whose mother was a Kriendler, has worked at "21" since he dropped out of New York University to wed in 1947. He started out plucking chickens in the kitchen and later worked as an assistant cashier before rising to the top. Today Tannen and his wife, Ellen, own a home with a swimming pool in Westhampton Beach and an apartment in New York. Tannen's daughter, 24-year-old Melissa, is a corporate advertising and promotion assistant; son Richard, 29, is keeping up the family tradition by working as banquet manager of the "21" Club.

The Texas operation notwithstanding, "21" in Manhattan remains the heart of Tannen's empire. Winston Churchill, the Duke and Duchess of Windsor, the Beatles and every U.S. President since FDR have, as Tannen puts it, "been through these hallowed halls." Has any celebrity not been to "21"? "Well, yes," he smiles. "Miss Piggy."