Don't jettison your French or Italian vacation dreams just yet.

European hotels, car rental companies and government tourism agencies are ramping up marketing and turning to creative payment plans, complimentary cell phone use and deep discounts to salvage the summer travel business. These efforts aimed at American tourists are intensifying as fluctuating exchange rates, rising airfares and a gloomy economic outlook threaten to deter the world's most lucrative travelers from crossing the ocean.

Visits to European countries by Americans -- who tend to stay longer, spend more and return repeatedly over the years -- have slipped as much as 5 percent this year compared with last year. But foreign tourism officials hope their summer incentives will stop that trend and help attract 13 million U.S. travelers by the end of this year -- the same number of Americans who visited in 2007.

"It's going to be tough, so we have to try harder," said Jean-Philippe Pirol, chairman for the European Travel Commission, a marketing organization that promotes Europe as a tourist destination.

To take the sting out of an unfavorable exchange rate, some hotels are guaranteeing that room rates won't rise as the greenback's value falls. The Hotel Lutetia and Hotel du Louvre in Paris are letting Americans lock in the exchange rate that's listed the day they book their reservations. And WorldHotels' collection of 52 independent properties throughout Europe does even better with its "Pay in Dollars" deal, which eliminates the exchange rate -- putting the euro on par with the dollar -- for U.S. residents who pay with cash or traveler's checks and stay at least two nights by Aug. 31.

But some travel companies are luring Americans in other ways. Auto Europe is offering car rental upgrades or complimentary use of cell phones or GPS navigation devices on some rentals. And Ardeonaig Hotel in Scotland is contacting past guests and touting the credentials of its chef, Pete Gottgens, who prepares locally grown ingredients in simple ways and has cooked for luminaries such as former President Clinton.

Why the appeals? Americans spend a lot, usually more than visitors from any other country, said Pirol, who is director of the French Government Tourist Office in addition to his role with the European Travel Commission. And Americans who vacation in Europe are likely to go back to the countries they visit. In France, for example, 30 percent of American travelers have visited the country more than five times, Pirol said.

A new study suggests there's hope for European efforts to attract U.S. tourists. A first-of-its-kind report produced by Waltham-based Global Insight for AAA predicts almost 6 million Americans will travel to Europe this summer, an increase of 4.6 percent over last summer.