Talk about exclusivity: the new Papaya Playa Project in Tulum, Mexico is so au courant, it's only open through May fifth this year. The pop-up hotel in Riviera Maya, with its 99 beachfront cabanas, is a pretty new idea in the luxury hotel world. The camp-like, eco-friendly escape, led by Claus Sendinger of Design Hotels, features rustic-chic, thatched roof accommodations complete with hammocks and mosquito netting so you can achieve that island castaway feel in the middle of the touristy mainland. --Toni Kervina