If you are going to ride the Duce more than once or twice in a 24 hour time span. Get the $5.00 24 hour pass. The same 24 hour pass will also be good anywhere on the Las Vegas Cat bus system. In case you want to make a side trip. However, the 24 hour pass or any LV cat pass cannot be used on the LV monorail system.
I ride the buses & The Duce a lot when I am there. And have found them to be a good way to get around. Even though sometimes it takes a little more time to get somewhere.
Dan