What's your favorite New York potboiler? The case of the Mayflower Madam (Sydney Biddle Barrows)? The Jean Harris murder mystery? The Claus von Bu low question?

Judging by the itinerary for the annual Valentine's Day "Lovers and Losers" tour of romantic New York, to be conducted Sunday by the 92nd Street Y, there is nothing new about intrigue here in the sidewalk jungle.

From Nelson Rockefeller to the Duke of Windsor, Cole Porter to F. Scott and Zelda Fitzgerald, J.P. Morgan to Consuelo Vanderbilt, chaperon Marvin Gelfand covers the obvious "love names" in the six-hour bus-and-walking tour, as well as some recherche' ones that were once as well known to readers of newspapers as Harris, von Bu low and Barrows.

* There's Madame Restell, New York's famous society abortionist. Operating from palatial quarters opposite St. Patrick's Cathedral on Fifth Avenue, Restell performed hundreds until she was caught in 1873 under the Comstock Law. She committed suicide.

* Elsie de Wolfe, the first professional interior decorator and the woman who made lesbianism "chic," according to Gelfand, through her so-called Boston marriage to Elizabeth Marbury.

* Emma Goldman, the radical anarchist and publisher of the journal Mother Earth, who promoted free love long before the hippies overtook the Village in the 1960s.

* Lily Langtry, the actress who parlayed her affair with King Edward VII into an acting career.

* Stephen Crane, the writer who protested the conviction of prostitutes in the Tenderloin district, even claiming falsely that he was married to one.

Not to overlook the site of the funeral parlor where Rudolph Valentino was laid out in August 1926. "When he died," said Gelfand, "it was said that love itself died."

Or the house where Kate and Spencer lived . . . Garbo's house . . . the house William Randolph Hearst bought for Marion Davies . . . Cole Porter's piano in the Waldorf Astoria and Fitzgerald's fountain in front of the Plaza hotel . . . Edna St. Vincent Millay's house . . . the memorial to Isadore and Ida Strauss . . . Who?

The Strausses were passengers on the Titanic, which sank in 1912. Rather than take her place with other women and children in a lifeboat, Ida Strauss chose to die by her husband's side. "Without him," she said, "life would not be worth living." Their neighbors back in New York put up a memorial to the couple. The name of the park at 105th Street and Broadway was changed from Bloomingdale to Strauss.

"I don't want people to think all New York love is jaded love," said Gelfand. "I always tell them, 'Don't forget the Strausses.'"