When you book your Las Vegas vacation with both air and hotel together, you really do save big. The way we are able to offer the discount is by taking advantage of subsidized rates courtesy of the airlines. The airline industry has become extremely competitive. As a result, many airlines have agreed to pay for part of your hotel stay.
The hotels are okay with it, since they still get paid the full amount. In addition, the hotels don't need to disclose these cheap nightly rates, since it is bundled with air, which would normally be a public relations problem if you just booked the hotel online (they don't want their own published rates to look high in comparision and it messes with price guarantees). Everyone wins in this situation. But don't just take our word for it, try doing an air/hotel search using the above form and see how much you save compared to booking air separately.