I tried to set both Zoyd's and the average settings on my PN51D8000. I feel that the average ones produce a little more balanced picture, but I think that might be because I watched it with some dim lighting in the room. I also found that most settings were just a little too dark for my liking, and that too much shadow detail has been clipped off (even when I tried to watch the screen in complete darkness). Setting the brightness to 55 seems to be the sweetspot for shadow detail, and also looks better in the "Expert pattern #1" from the advanced settings, as the second gray box from the top left of the screen is still visible with 55, but not 54.
I think I'll try setting up one set of values for day viewing and one for night viewing. Does anyone know how to unlock the Cal-Day and Cal-Night presets? I tried to access it from the service menu, but I got lost, and I thought I shouldn't mess with what I don't know.