In September I stayed at the MGM. The hotel was huge. Weather was hot in the day, and pleasant at night.
In December I stayed at the Mandalay Bay. Weather was like ours here at home, with a few sunny days. The pools and outside bars were closed for the season. If you want to bring back some souvenirs, make sure that you go to the old part of Vegas for your purchases – better prices. Also, a $2 beer in old vegas is $6 along the big hotels on the strip. But all drinks are free when gambling. I usually just gave them a buck for bringing me the beer.