I’ve long been a fan of ExOfficio’s undies because it is light weight, moisture wicking and will dry overnight after being washed in a hotel sink.
For men, there is a new Sol Cool Cooling Underwear ($38-$46) that combines cotton with wicking nylon fibers that will adapt to your body temperature.
Columbia, meanwhile has diamond mesh trunks for men that wick away moisture and are antimicrobial, keeping you dry and comfortable even on the steamiest days. Available from Amazon for $34 for two. There is also moisture-wicking underwear for women from Columbia and from other brands for men as well including from Patagonia.
Check out the options at www.REI.com where you might find some on sale! And you can wash them in your Scrubba wash bag–and a lot more hygienic than washing in a dirty sink or bucket! The product is especially helpful for those without access to convenient laundry facilities or for those on tight budgets, including backpackers, hikers, and campers. It’s kind of like a flexible washboard in a lightweight bag. All you do is add cleaning liquid, water, rub for a couple of minutes, and then hang the close to dry. $55.