I know we've already covered pants, but Grayson said he couldn't do without this baselayer: the SmartWool Men’s Midweight Bottom ($80). These are a fairly heavy—but still very comfortable and breathable—form-fitting bottom, really useful in cold climates. The Midweights have flat-stitched seams for comfort, and a traditional fly. Wool is wonderful because it’s a natural temperature regulator, so it has a wider comfort range than synthetics. The material can also absorb a lot of moisture and still keep you warm. And wool tends not to absorb odors—an important consideration when you’re wearing a pair of long johns for weeks.
The Alternate: Similar to the SmartWool bottoms are the 260 Midweight Leggings from Icebreaker ($100). Again, soft Merino wool in a fairly warm weight, great on their own or layered under trail pants, a shell, even insulated pants.