Depends on how picky you are. I got four free nights comped at the Rio last August. We went with another couple who paid full price for their room. You can read my full summary on trip reports, under Rio.
We tried to get on the same floor, but couldn't even get assigned the same tower. We got Imanpanea sp? and they got Masquerade. They switched rooms three separate times (reasons documented on my TR) and were not really happy w/Masquerade tower. We on the other hand, could not have been more pleased. Turns out the Imp tower is the remodeled one (and maybe they save this tower for players?). OUr suite was spacious, clean, and terribly comfortable...absolutely no complaints. The shuttle service was good although sometimes the lines for the shuttle were long. We found it easier most days to walk to Gold Coast and use their shuttle to the strip. Also GC shuttle begins at 9am vs 10am for the Rio shuttle. Overall, I wouldn't hesitate to book the Rio again (if it were comped). I'd absolutely insist on the Imp tower though!