The Deuce is a system of double decker mass transit buses that you can use to ride around town. The fee is $3 for a one way trip or $7 all day. You can travel from the strip to downtown and back. The 2nd floor of the bus usually makes for a great view.
The main downside to the deuce is speed. They tend to be a bit slow. If you are going from the strip to downtown, expect a trip of up to an hour.
Some walking is worthwhile though
Depending where you want to go, you may want to get a cab. Depending on where you want to go in Vegas, you are looking at $6 to $25 one way. If you want to get a cab, go to the front of most casinos and you will find plenty.
If you are going to be doing any travel outside of Vegas, or if you are frequently traveling around Vegas, you may want to look into getting a rental car. Rentals can be picked up at McCarren Airport if you are flying in, or you can usually arrange for one at most casinos.
Las Vegas Monorail
The Vegas Monorail is an option for the strip. Stops include Sahara, the Hilton, the Convention Center, Imperial Palace, Flamingo, Paris, and MGM. A one way ticket is $5 and a full day is $12.
When going to Vegas, investigate the areas where you are staying and the best options for getting around. Doing some planning ahead of time will allow you to get around Vegas in the quickest time possible.