Mid-layer聟so, something to wear under a shell? That聮s what I like to do. It gives me a lot more versatility. I pack a shell, a cold-weather mid-layer and a not-so-cold-weather layer. If it聮s really cold, I can wear them both.
Micro Puff JacketMy current favorite is the older version of 聮s Micro Puff Jacket ($180). It聮s a trim piece that uses synthetic insulation, so it stays warm when it聮s wet. Its slick nylon shell layers beautifully under another piece. And it can be worn on its own. My slightly older version is a pullover with a short zipper, which I like. But the full zip adds a little versatility with very little weight/bulk penalty.
Otherwise, just about any midweight fleece makes a good cold-weather mid-layer. 聮s Pumori Jacket ($99) is made from Polartec 200, which is warm and not too bulkly, so it layers well.
For a first layer, I like wool, such as 聮s Bodyfit 200 Mondo Zip ($70). It聮s an excellent midweight base layer with a zip turtleneck. Under a fleece or Micro Puff, it聮s super warm and cozy. It works by itself, too, under a shell. I also like 聮s Microchill Zip T ($55). It聮s made from Polartec 100, so compared to the Icebreaker offers about the same warmth and a little better fast-dry ability. I do find wool to have a really wide comfort range, however.
The is now online. Go ahead, get everything you wish you had gotten over the holidays.