"Only in San Francisco" is the slogan of a marketing campaign launched by the convention bureau earlier this year in hopes of getting the city's tourism-dependent economy back on track.

The phrase has taken on new meaning in the weeks since 4,000 hotel workers went on strike and then were locked out by 14 of the city's most popular hotels.

The standoff is part of a national effort to gain leverage against the corporations that now run most of the country's big hotels, but only in San Francisco were the workers bold enough to go on strike. And in this pro-labor town, they've been rewarded with outspoken support from political leaders even as the city tries to rebuild the tourism that pumped more than $6 billion into the local economy last year.

With both sides preparing for a months-long conflict, visitors seem to be shrugging off the noisy pickets and reduced services as a colorful inconvenience -- mere reminders that ultra-liberal sensibilities are as much a part of the city as cable cars and earthquakes.

"If anything, it's a little excitement," said Trent Blizzard, a Coloradan whose only complaint during a property managers conference was that the Sheraton Palace Hotel's bar was closed during lunch. "The picketers are very nice."

Cheerful resignation wasn't exactly the reaction union leaders were aiming for when they called a two-week strike against four hotels on Sept. 29 to protest stalled contract negotiations. The action spread when 10 other properties involved in the talks locked out their unionized workers two days later.

Since then, the two factions have met three times under the eye of a federal mediator to iron out differences over wages, employee health care costs and the main sticking point -- the length of the new contract.

The employers are seeking a five-year contract, but Unite Here Local 2 -- the union representing hotel housekeepers, bell men, cooks and other hotel service employees -- wants a two-year contract that expires in 2006.

That's when unions in New York, Chicago, Boston and other major cities will renegotiate their labor pacts, and the unions want nationwide leverage against the corporations that own and run many of the nation's hotels.

The issue is so vital to both sides that a quick resolution to the impasse could be hard to come by. Local 2 has warned its members to be prepared to be out of work for up to three months, according to picketing workers.

"What gives this particular struggle some historical significance in recent labor history is precisely the idea and the importance of a transnational strategy," said David Kowff, a spokesman for the union's national arm.

Hotel workers in Los Angeles and Washington, D.C. authorized strikes at the same time as those in San Francisco and have virtually identical contract demands, but union leaders there have yet to call for walkouts. It's a matter of leverage, again: 85 percent of the hotels in San Francisco are unionized, compared to 50 percent in Washington and 45 percent in the central business district of Los Angeles.

The 14 downtown venues at the center of the conflict account for about a quarter of San Francisco's 32,500 hotel rooms, but they include such landmark properties as the Westin St. Francis, the Intercontinental Mark Hopkins and The Fairmont -- places where customers expect four-star service, not chants of "1-2-3-4, don't go through that hotel door."

It took days before police eventually persuaded the union to tone down the noise from the pots, pans and buckets picketers were drumming from 7 in the morning to 10 at night. Police also belatedly warned motorists that they too could be ticketed for excessive honking.

Mayor Gavin Newsom has gone out of his way to appear neutral, but he also has been urging the employers to agree to a 90-day cooling-off period that would allow union members to go back to work while talks continue. The hotel operators have refused.

"There is nothing to say that in 90 days the union won't call another strike," said Cornell Fowler, a spokesman for the 14 hotels. "It's too expensive for the hotels to just ramp up again. The fact remains the only way this labor dispute is going to get settled is at the bargaining table"

City supervisors heard the workers' complaints firsthand at a hearing Friday. The hotel operators declined to attend. Supervisors are expected to approve a resolution on Tuesday condemning the lockout and urging the San Francisco Convention and Visitors Bureau to warn visitors booking reservations that they might be crossing picket lines.

"The economic impact of the lockout is obviously a concern to the city, but our concern about that can't make us ignore the merits of the argument that led to the strike itself," said Supervisor Matt Gonzalez, the Green Party politician who organized the hearing.

The unions have claimed some victories -- some Fashion Week events were canceled this week -- but the convention bureau says it's still too early to know whether the dispute is driving away business. Large meetings that were booked years in advance and couldn't be relocated at the last minute have blunted some of the impact, since conventions bring in about a third of the city's visitors, said bureau vice president Mark Theis.

"At least the large conventions we pretty much have our arms around, they recognize this is not a San Francisco-specific issue. They realize it's a national issue, that there are expired contracts in Los Angeles, Atlantic City, Washington, D.C. and this could bleed into something larger," Theis said.

David Dennis, a spokesman for online travel service Expedia, said the site has posted warnings about the labor strife that visitors can see when they click on an affected hotel. "We want people to know what to expect, just like we want them to know if there is 24-hour room service or a pool," he said.

So far, hotel guests seem to be weathering the situation better than the managers who had to fill in on housekeeping duty before replacement workers were hired, or the union members picketing round-the-clock, even in the rain. To get $200 a week in strike benefits, they must put in 30 hours a week on picket duty.

George Merced, a houseman at the Four Seasons until he was locked out from his job, said he has seen women carrying infants on the picket line and another worker collapse with an epileptic seizure. He figures he'll need to find another work if the talks aren't resolved soon.

"Management and the union, I don't know if they care," Merced said. "We need some action. I'm not wasting my time."