New research reveals which nations and cities have the biggest appeal in 2013 for lesbian, gay, bisexual and transgender travelers, one of the tourism industry's most valuable niche demographics.

LGBT tourism now accounts for a sizable portion of the overall travel market, and Out Now, one of the world's biggest LGBT market specialists, predicts that LGBT travelers will spend some $165 billion in 2012 and even more the following year.

According to its latest survey of prospective travelers, trends will change slightly over the next year. The United States, for instance, will lose its top spot to France, falling from first to third place as a desired destination country for the more than 6 percent of the total global tourism industry who identify as LGBT. New York City, however, will retain its No. 1 spot as the most popular city for LGBT travelers in 2013.

The United Kingdom, meanwhile, will move up from fourth to second, apparently basking in the post-Olympic glow. London, too, will move ahead of Paris to No. 4 on the list of popular cities.

"This year it seems that Team GB can take credit for a few more wins as both London and the UK have seen significant improvements in their appeal to this market," said Darren Cooper, senior consultant at Out Now, based in London. "When you consider the scale of the LGBT market opportunity, moving up or down a notch can mean hundreds of millions difference in tourism revenues for a destination."

Cooper said tracking global LGBT tourism trends helps the industry stay informed in order to optimally position for what is widely regarded as a lucrative market. He added, however, that there are regional differences between respondent countries.

"India and Turkey were quite different from many of the other countries," Cooper noted. "If you are looking at targeting emerging markets you need to understand these differences if you are to succeed.

"Interestingly, London was the top European destination for many markets such as the U.S. and Australian samples, but respondents from Latin America were generally more interested in Paris than in London. It was also quite noticeable this year that Latin American LGBT respondents in particular have turned away from the United States as a desired travel destination for 2013 and beyond."

The survey also reveals that the euro zone crisis has had little effect on the decision-making process of LGBT tourists. Greece (No. 9) will crack the top 10 for the first time next year, Out Now predicts, joining similarly affected countries like Italy (No. 4) and Spain (No. 5).

Down under, Australia (No. 6) will place the highest in Asia-Pacific, while Argentina (No. 10) will top the list of South American nations. Germany (No. 7) and Canada (No. 8) will also make the top 10.

The survey data from Out Now comes from nearly 100,000 respondents in 24 nations who were asked which countries and cities they wanted to visit in 2013. It is the first data to be released from the "Out Now Global LGBT2020 Tourism Report," to be revealed in full this November at the World Travel Market, a leading global event for the tourism industry.

Click "Start" for a complete look at the most popular cities for LGBT travelers in 2013.

Data Source: Out Now Global LGBT2020 Study www.OutNowBusinessClass.com

New York retained its No. 1 spot.

Rio de Janeiro climbed one spot to No. 2.

Sydney fell one spot to No. 3.

n London, the most iconic sites protected by the World Heritage status include the Tower of London to catch a glimpse of the Crown Jewels. The walks will be incomplete if you do not pass by the burial grounds of talented Britons Charles Dickens to Charles Darwin at Westminster Abbey.

San Francisco retained its No. 5 spot.

Paris fell two spots to No. 6.

Buenos Aires retained its No. 7 spot.

Tokyo retained its No. 8 spot.

Amsterdam climbed three spots to No. 9.

Los Angles/West Hollywood climbed one spot to No. 10.

Rounding out the top 20 were Las Vegas, Hong Kong, Melbourne, Barcelona, São Paulo, Berlin, Mexico City, Rome, Cape Town and Miami.