Part of my winter clothing strategy is based on shot winters and the ability to reuse layers in sprint and fall. Also how often you ride in the winter. Given that I live in wimpy winter land, I prefer two layers so that I can use the outer pants in warmer temps. The Pearl Izumi AmFib tights do get a lot of callouts here.

I have a pair of Asic running tights and Novara Headwinds pants. That keeps me OK down to 37.