I have the necessary maps and profile plots (done with PSTricks) delivered
to my client so I'm back to SQL, Python, and R for a while. 
My thanks to all who helped by answering my questions.
I look forward to seeing more extensive documentation on the multitude of
options with m.nviz.image and the v.distance measurement capability fully
functional. While these are not explicitly spatial analytical tools quite
often we (at least, I) need to make presentations to non-technical
decision-makers so display-quality maps are needed. (Try explaining a
flowline or flow accumulation map to a jury of lay-people!)
I shall return, as McArthur said.
Rich