At the end of the hiking day, you're only as good as your baselayer—just ask the person sharing the tent with your smelly self. Wool baselayers cut down on stench, but they're often itchier and heavier than their synthetic counterparts. That ended a few years ago, though, with the introduction of the mighty merino, an ultra-soft, extra-light wool that let you have it both ways.
Enter the Ibex Woolies Zip T-Neck baselayer: Designed for cooler, winter-to-early-spring adventures, the shirt promises breathability, warmth, and flexibility in a lightweight, stylish package. On a mid-February ski weekend in the Colorado Rockies, the Woolie delivered by wicking sweat while we roasted under a high-altitude sun; moments later, when oncoming cloud cover dropped temps by 10-15 degrees, the top switched roles and kept us toasty with the addition of just a midlayer. The Woolie comes in crew-neck versions as well, but we'd recommend the zip-neck for added winter versatility.
When faced with the stink test, the Ibex tested even better than other wools we've tried. After that ski trip, a 7-mile snowshoe, and two or three days worth of cold-day jogs, the Woolie absorbed a surprisingly small amount of my potent man-musk. It didn't smell Snuggle fresh, exactly, but I wouldn't clear out a bar either—the same certainly can't be said of stinky synthetics. (Full confession: I haven't even washed it as of this writing...but I will. Promise.)
Caveats: While solidly breathable, the Ibex Woolie is probably too warm for any heavy-on-the-cardio adventures beyond the cooler days of spring (cool summer nights on the town are probably OK, though). If you're wearing this baselayer solo, confidence is a must, as the tightly-wound, New Zealand merino cloth is Catwoman clingy. Also, at $70 for just a baselayer, you'll pay a fairly hefty price for all that versatility.
Still, the Ibex Woolie will likely cover all your baselayer needs from October to May, and you might be able to go that long without washing it (OK, for the sake of your trail partners, don't really try that). When it comes to baselayers, it's another compelling reason for you to say "make mine merino."