Las Vegas has luxurious hotels, your bookie drives a Cadillac and the online books rarely pay you out because people are idiots.
Each sets lines for fools to bet on, and they always win in the long run.
To make things easier, each has something called the prop bet. It's a bet based on something else other than the direct outcome of the game, but it is somehow related to the game.
For example, you can bet on something like who will have more passing yards: Mike Vick vs. Eli Manning, with Vick -15.5 yards.
A bet like that can be found in Vegas through a bookie or an online book. But a bet that has nothing to do with the game cannot be found in Vegas, which means you cannot bet on the length of the national anthem at the sportsbooks in Vegas.
Here is the law about it according to Vegas.com:
Under state law, wagers must involve the outcome of 'athletic contests' rather than elections or votes of any kind. This means you cannot even bet on who will win awards such as the Most Valuable Player, Rookie of the Year, Cy Young and the like.