Om XM Radio, my default is 70s on 7, but I work in some 60s on 6, Bluegrass, Country, and R&B. If I'm running around on Sunday and the race has started, I'm listening to the rhythm of 800 horses on the NASCAR channel.
My "test album" for a new audio setup (well, it used to be an album) is Loggins and Messina's MotherLode. The mandolin (at least I think it's mandolin) work on that collection is great.