A difficult year for tourism is ending on a high note thanks to two large back-to-back conventions and the Honolulu Marathon, but the good news is being tempered by the lack of big-attendance events in the first half of 2010.

Waikiki hotels, businesses and restaurants say the upcoming Honolulu Marathon, coupled with two conventions (of the American Dental Association in October and Jehovah's Witnesses in November) have provided a big economic boost during an otherwise gloomy year for Hawai'i's top visitor destination.

Both conventions generated an estimated $100 million in visitor spending.

And the marathon is expected to rake in about the same.

But the good times are expected to be short-lived: The Hawai'i Convention Center is expecting far fewer events in 2010, compared with this year, and many of them are scheduled for the latter half of the year. In all, 17 events are scheduled for the center in 2010, and they're expected to generate 525,000 room nights.

In 2009, about 30 events generated 628,000 room nights.

Joe Davis, convention center general manager, said there is still hope that more conventions will be scheduled for 2010. He added that 2009 was a big year for the convention center on any standard because of the two large gatherings.

The international Jehovah's Witnesses convention, which wrapped up Sunday, was the largest event of the year for the Hawai'i Convention Center, bringing in some 30,000 people for one of two four-day sessions. The American Dental Association was the runner-up, bringing in 24,000 attendees in October.

Meanwhile, some 22,196 runners have signed up for the Dec. 13 Honolulu Marathon.

Although the conventions and Honolulu Marathon don't make up for months of slumping visitor numbers, tourism industry officials say they do provide a welcome boon for merchants and hoteliers who have been struggling to remain afloat through one of the worst recessions the world has seen.

"This was just a home run for Waikiki," said Rick Egged, Waikiki Improvement Association president, of the back-to-back events. He added they not only boost Waikiki's visitor numbers, but help businesses islandwide.

In Waikiki yesterday, shops and restaurants were still bustling with Jehovah's Witnesses, and some merchants said they had seen up to 20 percent increases in sales during the convention. Others said they were looking forward to the marathon, which brings thousands from Japan, where the yen is strong.

Estrellita Schweizer, a sales representative at Hawaiian Accessories in Waikiki, said that sales first boomed with the dentists and then with the Jehovah's Witnesses. "It really has made the difference," she said.

Mygo Hawaii, which sells tie-dye wear and other items at the Waikiki Marriott, saw revenues jump during the dental association's convention. "We had really good days," said owner Solange Globen, adding Jehovah's Witnesses haven't been as interested in her shop. In November, sales were down.

But Globen is expecting them to pick up again during the marathon.

In the lobby of the Waikiki Marriott yesterday, there was a big line as Jehovah's Witnesses checked out to head home. Many others, though, were spending a few more days in Hawai'i. Dolly Kelley of Illinois said she saved up for months to take the trip and would spend a little extra time in the Islands to take in the sights. "It's my first time here," she said. "It's very lovely."

During her trip, she spent about $500 on gifts alone, Kelley said.

The Honolulu Marathon is expected to bring its own windfall, which some say could be slightly higher this year because the yen is stronger than the dollar, so Japanese flying in for the race might be willing to spend more than in the past.

Jerry Agrusa, professor of travel industry management at Hawai'i Pacific University, said marathon-goers are historically good spenders anyway — with the average Japanese marathon runner spending about $300 a day. Agrusa has for years conducted a survey to determine the economic impact of the race.

Murray Towill, president of the Hawai'i Hotel & Lodging Association, said hotels are bracing for the prospect of a lean convention year in 2010, even while they celebrate the recent increase in visitor numbers thanks to the gatherings.

Towill added that hotels especially enjoy convention goers because they often have more disposable income, because they're professionals, or are willing to spend more because their company helped cover some costs of their trip.

Part of the slump in conventions next year could be because many corporations are reluctant to schedule gatherings in Hawai'i, especially during difficult economic times. The convention center has already seen declines of corporate conventions in the last two years because of the recession, officials said.

But there is hope that will change as the economy improves.

David Uchiyama, Hawai'i Tourism Authority vice president of tourism marketing, said the Jehovah's Witnesses and dental association conventions were "huge in terms of impacting" businesses and hotels in Waikiki.

Although 2010 is not shaping up to be a strong year for conventions, he added that some are optimistic that will change as the economy improves.