The Cosmopolitan of Las Vegas has started taking reservations for its Dec. 15 opening, the resort announced today. The 2,995-room, 50-story resort-casino between the Bellagio and CityCenter is planning a soft opening in December with a grand opening celebration on New Year’s Eve weekend. Prices on opening night start at $300 for a 620-square-foot studio with a 110-square-foot private terrace, and peak at $510.