Commuting, Fat Biking, Touring, I go chamoisless.

First thing I had to solve was type of underwear, as I needed something supportive and that didn't have a crotch seam. After a few false starts (Target, Ex Officio) I've settled on Arcteryx Phase SL Boxers. Tried a pair on sale, then bought another when it worked. They are very light, very supportive, and have a bit of a seam, but it's a nice flat one. They also dry very quickly, so I rotate my two pair, handwashing one pair every morning or evening.

In shorts weather I wear a pair of Swrve Durable Cotton shorts to commute ($90 regular, but I bought them for $30 from someone who bought the wrong size) and Zoic Ether MTB shorts for trail riding (on sale for $30 through REI Garage). In cold weather I wear Montane Terras or Haglofs Rugged Mountain II pants (Sierra Trading Post). My commuter/tourer/trail bike has a Brooks B-17 saddle, the fat bike has an Ergon SME3 Pro.

When I ride my road bike I still wear bike shorts, but not for anything else.