J, always gotta hate! Searching on this site is awful, and it's always fun to kick the conversation around again, since it is always changing.
for my "audiophile" 2 channel system, I use Vivaldi's "Le Quattro Stagioni" the Standage/Pinnock concert recording on period instruments. The scale ranging from silence to full orchestra is impressive on my big Maggies and class A amps, the subtle details of the viola are amazing. Particularly track 10.
for my surround setup in my theater, I use the 5.1 remaster DVD-A of Nick Cave & the Bad Seeds album "Murder Ballads" track, "O'Malleys Bar" (don't demo this to your mother, very disturbing and offensive) The twangy, out of tune piano and deep, haunting effect of Cave's voice, combined with the theramin and blue's rythm backing is a particularly effective encompassing sound