Big Sur, California—Treebones ResortYou should sleep outside at least once in the California gem that is Big Sur. And while not quite as comfortable as the other star beds here—it’s BYO sleeping bags and pillows, though there is a futon mattress—the so-called “Human Nest” is a creative way to check off that box. The resort calls it “extreme eco-sleep.” Guests hike into the campsite and bring their gear up a ladder and into a human-size nest made by a local artist of woven wood, where starlight shimmers through the spaces between the branches.

Source: http://www.outsideonline.com/adventure-t...

Admittedly, extreme.  There are other more comfortable retreats featured at the link.