South Lake Tahoe for more to do type stuff for your ladies. North Lake Tahoe would also be pretty boring. You could also do Reno I suppose.
During winter though, it is still pretty much based around the ski areas. If your ladies like casinos and drinking all day, they'll probably be fine. The Lake is gorgeous too.
I am not sure what Salt Lake offers but it has to have something? Maybe?
Aspen, expensive, but that is a good fuck around town no doubt.