It just so happens that all five of them are in Las Vegas. #5 Luxor, 4,407 rooms, 35 floors, #4 Mandalay Bay, 4,426 rooms, #3 Wynn 4,748 rooms, 45 floors, #2 MGM Grand 6,920 30 floors, #1 Venetian 7,092 rooms 36 floors. This last one is actually a combination of two adjoining hotels. The Venetian and the Palazzo. So, this list is not entirely correct.