MGM Grand

With over 5,000 rooms, the MGM Grand qualifies as the biggest hotel in the world - a fact made obvious by the enormous 171,500 square-foot casino. They call it The City of Entertainment, and it certainly has enough within its walls to be called a city: dozens of restaurants and bars; a shopping plaza; pools; a spa; three entertainment venues including a stadium-sized indoor arena; an outdoor theme park with thrill rides; convention and meeting space; a walk-through animal exhibit; children's activities and entertainment; and much more. Rooms start at $99 per night for a standard-double and go up from there.