Public Transportation in Vegas?

[Intrepid]

I'm planing to spend a few days in Vegas and will compete in the first event of the WSOP at the Rio. I would appreciate help deciding whether to rent a car. I've been told that a $5 shuttle can get me from the airport to my strip hotel. Can someone please describe the convencience and expense of using public transporation to get up and down the strip, and to travel between the strip and the Rio? Any free shuttles or monorails?

Thanks!