Mass extravaganzas aside, Asia Pacific Travel's Winnie Lu acknowledges that the trip isn't for everyone.
"Two kinds of people go there: those who have been everywhere, and academics studying Korean or Asian culture," she says.
Lu wouldn't go so far as to call the trips "fun. But they're interesting, educational. And once you're there, you don't feel threatened.
"Of course, you don't see anything they don't want you to see."
New turf in Afghanistan
Travelers who find exotic locales such as Nepal a "been there, done that" destination are turning their sights toward Afghanistan.
The capital, Kabul, was once a popular stop on the Hippie Trail. But the Russian invasion in the 1970s, followed by Taliban rule and then the post-9/11 bombings, had snuffed out tourism for decades. Now, a number of adventure travel companies are leading tours into relatively peaceful central and northern Afghanistan.
"What's made it possible today is a large part of the country is stabilized," says Jonny Bealby, whose U.K.-based Wild Frontiers has been running tours in Afghanistan since 2003.
"The violence is localized. As long as you steer clear of those areas, a lot of Afghanistan is getting along pretty normally."
Still, tourist numbers remain small — about 1,000 a year, he estimates. The typical circuit is concentrated in the Hindu Kush Mountains of central Afghanistan, where Bamiyan, site of the giant stone Buddhas destroyed by the Taliban, and the surreal blue lakes of Band-i-Amir are located.
Andre Mann, co-owner of Kabul-based Great Game Travel, sees potential growth in the eastern panhandle, in the remote Wakhan Corridor where Tajikistan, Pakistan, China and Afghanistan come together. It's a pristine spot known as the "Roof of the World."
Getting there requires a five-day drive over dusty roads just to reach the trailhead. Great Game's 12-day treks using horse and yak caravans cross 15,000-foot passes, where participants camp out with nomads.
"It's untouched by modernity," Mann says. "It may be the last frontier — anywhere."