The big guys don't come down unless you get really heavy snow. From my house I can glass big guys up on the windblown knobs even in January when the smaller deer are down at sea level.

The best hunting for the really big bucks (in my opinion) is early and very high, I mean right up in goat country. If you're high enough, you can glass an awful lot of open country.

Second best would be November, during the rut. But then they're down in some pretty thick country right along with the bears.