Thanks for all the feedback and suggestions.

Coincidentally, we went on a nice little 52-miler on Saturday (we've been getting absolutely gorgeous weekend weather in Michigan for several weeks!! ) and on the second half, I noticed a burning in the nether regions, and appear to have gotten a little chafing right in the crease between my leg and buttock. First time this has ever happened to me, and I'm used to doing rides in the 40- to 60-mile range. However, now that I've experience this first-hand, I'm going to be sure to both pack a couple of different kinds of seat lube and USE them each day I ride. I can see how this could quickly make a multi-day ride real agony, as the little bit of chafing I have now makes me very disinclined to climb on the saddle even today!!