The Monorail rocks if you are working or attending a convention and your hotel is near one of the stations. Those hotels are MGM, Bally's, Flamingo, Imperial Palace, Harrah's, Old-Hilton, and Sands (which is no longer open)! If you are staying at another hotel you can walk over but it may be a long walk to get to the station. Walking through the MGM to get to the monorail station is a long walk and you will get lost at least two times.
I typically will buy a $28 three day pass and this will save you money over getting a taxi every single time plus you do not have to wait in that traffic on the street.
The monorail also does not have a train driver it is all computerized. I think there is some guy sitting in a room with a joystick and he thinks he is playing a PlayStation game about transportation.
Just a quick note the monorail does not start running until 7am in the morning, so if you are trying to get to work early you will not be able to get on it before that time. I found that out a a few years ago, when I got to the station at 6:45am. But it is really cool because at 7am the chain link fence automatically opens by itself and the gates start working. It is a site to see. Really no one works here!!! Yeah you have to use machines to buy your tickets too! At least there are no customer service issues here! How can I get mad at a machine?