Hmmm. I was just checking the forecast for West Yellowstone, not too terribly far from where youre going, and they expect snow next week! So Im sure youll have a great trip, but as you no doubt know (being from Montana), its apt to be chilly.
So, Ill be brief: You need different briefs. I mean, cotton? They must never dry out when youre hiking and sweating. I havent worn cotton underwear while doing anything except writing Gear Guy columns for years.
You can go into any outdoor or sporting goods store and choose from a wide array of undershorts in synthetic materials such as DuPont Coolmax or polypropylene. All will work well. But a few materials and designs stand out. Ex Officios Below the Belt Briefs ($18; www.exofficio.com) are a trimly cut model made from nylon and Spandex that dry fast and are treated with an antimicrobial. Very nice. For something a little warmer, try REIs Midweight MTS Briefs ($16; www.rei.com), which use a polyester fabric that wicks extremely well so you dont chafe.
That hot design in mens underwear, however, is the boxer brief. These are shaped like boxers, but are a little shorter and use stretchy materials so they hug the body. The result is a brief that has plenty of support and that does away with seams around any sensitive areas. Patagonias Active Boxer Briefs ($26; www.patagonia.com) are an excellent example of this design. Theyre very comfortable and fast-drying, maybe the perfect brief for a trip such as yours.
Check out this years more than 400 must-have gear items, including a comprehensive hiking section, in the 2006 Buyers Guide.