I wouldn't worry much about smokey rooms just ask for non-smoking and stay at a minimum 3star hotel. I can recommend a few good options if I knew your price range,
also if you have a couple hotels in mind. Here's a good list of
Las Vegas hotels to get an idea of whats there.
Mid-January should be a good time since CES will be over. I won't have any promo codes for January until about Sep-October which would help you get the best hotel deal.