When I went on my 9 day, 550 mile ride across AZ, I used Desitin (sp? the stuff for baby diaper rash). It numbed the area a bit - which was nice during the last three days! - and helped prevent infections from the heat, moisture, etc. Even if you use something else, you might consider a topical antiseptic (especially one with a bit of numbing properties - did I mention that?) so that any potential infections can be headed off.

Another important thing - the minute I got into camp, hotel, where ever, I took the shorts off, washed well, put on a little more desitin & put on some loose pants. ahhh, heaven!