Sherpa Half Zip might be your new best friend, as far as layers go. Comfortable as a low-key everyday style, but built with enough tech to provide a functional mid layer when the mountain environment calls for it. 275g sherpa resembles the original poly fleece of the 70's, and the snap pocket has a parking spot reserved for your trusty pen. The deep neck zip is convenient on the fly, and an adjustable draw cord at the lower body opening gives you options.
275g sherpa fleece
Deep neck zipper for easy access and venting
Hidden adjustable draw cord at lower hem
Snap closure chest pocket with pen garage (shoot with sharpie or pen inserted)
Airpill flag label at chest pocket