What are you going to do while you're here? Skiing? Sight seeing? Let us know and that will help out. For instance, Denver is closer to the slopes, but IMHO there is more to do and see in C. Springs (outdoors). Denver is probably better if you are looking for nice hotels, museums, night life, concerts, fine dining, etc.
In terms of snow...we really don't get that much. Seriously...with the exception of a couple big storms each season, we just get a couple inches here and there. The big snow is up in the mountains. To be honest, ATs are much better in the snow than MTRs (unless it is 12"+), but I guess you could bring along some chains if you're concerned. Keep in mind that people drive Honda Civics up to the resorts on a regular basis with little to no problem. Contrary to popular belief we don't have 12-36" of snow on the streets at all times.
Let us know what your plans are and then we can provide some guidance.