Bill, in those situations, I would still stay away from denim. I would use canvas pants like Carharts or Dickies, or wear BDUs made from ripstop ny/co. Canvas pants are tougher and dry faster than denim. BDU's are lighter, and dry even faster, and are still really tough.

A third option that I want to try some time is to sew patches of Cordura on my nylon pants to spots of heavy wear. This would hopefully make them more durable and still dry really fast.