I stayed at the Rio with a conference in July. It was dirty, musty, mildewed, the pool was closed a lot during normal hours of operation, the food was okay. The game floor was run-down, dirty, stinky (like someone crapped their pants-all the time). The elevators were often crowded and we had to wait in a mob to get on an elevator. There were always long lines at reception and concierge. We were there on weekdays. The shuttle services was poor - always waiting for the second or third shuttle to pick us up from the strip to come back. A cab would've been easier and worth the money. We had a great rate but it was similar to better kept hotels on the strip.  I would not ever stay there again with all of the other options in Vegas. I only stayed because of the conference or I would've changed hotels after the first night.