It is unbelievable how well the ventilation system works in that hotel. Besides ventilation, they must use scrubbers as well, because there is no smoke to be seen at all and I know people smoke like fiends in LAS.

I have always asked for smoke free rooms and they are smoke free. If I am not mistaken, the entire floor is smoke free as well at the Hilton, but even the Gold Coast was good about giving people rooms which were not smoked in. I think you should be okay, but as the above poster said, if you are not happy, ask for another room. It's not like they don't have several thousand to choose from .