Tierra Atacama, San Pedro de Atacama, Chile
Best for: Desert Adventure
The Atacama, in northern Chile, is one of NASA's preferred research destinations. Why? Because the high-altitude terrain of the world's driest desert bears an uncanny resemblance to Mars. Tierra Atacama tucks into the arid landscape with luxe minimalist style. While nearby 19,423-foot Lincancabur volcano dominates the view, raves go to the hotel's fairy-godmother service. Linger in private wooden hot tubs or get spackled with volcanic mud at Tierra's spa, but don't miss the expeditions—on foot, by mountain bike, or by jeep—to see high-altitude lagoons, salt flats, and altiplanic villages. At night, terrace bonfires and Chilean wines warm stargazers. From $970 per person, all-inclusive; tierraatacama.com
The Lodge at Valle Chacabuco, Patagonia, Chile
Best for: Location.
Lodge at Valle Chacabuco
The lodge at Valle Chacabuco
Situated in the soon-to-be-opened Patagonia National Park, which has the potential to rival Torres del Paine for its remote wilderness beauty, this lodge is big news in Patagonia. Not only is the former estancia one of the largest grasslands-recovery projects in the world—thanks to Conservacion Patagonica, the land trust founded by American philanthropist Kris Tompkins—but the hiking, wildlife, and infrastructure are first-class. The six-room, pitched-roof stone building was inspired by Ahwahnee Lodge in Yosemite and sits in the foothills of the southern Andes. With dark wood walls, cream sofas, and multiple fireplaces, it's ranch elegance at its finest. Plus it's sustainable, with fresh greenhouse vegetables and solar energy. Outside, the park is full of guanacos, endangered huemul deer, flamingos, and pumas: a far cry from the overgrazed estancia Chacabuco was when Tompkins took over in 2000. Lodge guests can get a jump on exploring the more than 600,000 surrounding acres; rumor has it the park will officially open in November 2011. From $400 per person; firstname.lastname@example.org
Karanambu Lodge, Rupununi, Guyana
Best for: Unexplored Rainforest.
Karanambu is known for founder Diane McTurk's commendable work rescuing giant river otters deep in southwestern Guyana's rainforest. The McTurk family, who have lived nearby since 1927 and founded a conservation trust in the region, are magnanimous hosts (just ask David Attenborough or Jeff Corwin). The savannah tours, run by the lodge's naturalist, birding, and indigenous guides, are adventure-packed: go deep in flooded forests, tag caiman with researchers, or hike to Amerindian villages. Accommodations are brick-and-thatch huts with mosquito nets. Come nightfall, giant lilies blossom and a century of pioneer tales unfold over Karanambu's signature rum punch. From $180 per person; karanambu.com
Caiman Ecological Refuge Lodge, Pantanal, Brazil
Best for: Jaguar Encounters.
The Pantanal—the world's largest wetlands, in southern Brazil—reels in avid wildlife watchers. It also happens to be the heart of Brazil's cattle country. Balancing responsible ranching with conservation, the Caiman Lodge has earned accolades for keeping rare species like the jaguar and the hyacinth macaw alive. Skilled naturalists lead expeditions to flooded marshes and lakes, while guests bunk in two luxe sustainable lodges featuring private decks with a pool and hammocks, solar-thermal-heated showers, and waterfront balconies from which to spy passing capybaras. From $523 per person; caiman.com.br
Estancia Menelik, Patagonia, Argentina
Best for: Galloping to Infinity.
Estancia Menelik, just outside ultra-remote Perito Moreno National Park, is a windy haven of turquoise lagoons and snowcapped Andes. Gauchos still work the steppe, and condors and guanacos easily outnumber humans. Stay in the historic family casco, a rustic ranch house, or in simple bunkhouses. After a day in the saddle exploring tufted grasslands and the rugged Sierra Colorado, uncork a vintage malbec and dine on the estancia's own natural beef and garden vegetables. From $125 per person in the casco; rides extra; cielospatagonicos.com