Thanks, everyone.
The contrast enhancement came from some further experimentation of methods I have described elsewhere using two color layers, inspired by the split-tone process for black and white images.
I was especially pleased with how the first one came out. This is the original, unprocessed version of the photo:
The highlight contrast mask was done with orange and the shadow contrast mask was done with black. I then applied a very light vignette mask, light USM, and bump map to finish it off.
I have to give most credit to the great SMC-A 35-105/3.5 lens, although after about an hour or so I was wishing I had followed my original instinct to leave the overweight son of a gun at home.