Phil - You do have the travel to contend with, and you combine with a home leave from your job? Don't know your situation.
We have been combining the NHC with some beer travel and other recreation.
2009 in Oakland was combined with a few days near Yosimite. I hiked to the top of Yosimite falls one day, and that was big fun.
2010 in Minneapolis was combined with a stop at New Glarus, and a stop to see my sister and BIL in Northern WIsconsin.
2011 San Diego will be seeing friends in Orange County, a niece who recently moved to Temecula, and maybe Death Valley or some other parks.
We try and get extra out of the travel to NHC.
Edit: Once the conference starts you hardly have a chance to see the sun, let alone the city and area.