Music: Faces in the Crowd

Who's playing at the local rock palace? One way to find out is to look at the marquee. Another, says California Promoter Steve Wolf, is to watch the crowd strolling—or floating, in the case of heavy grass consumers—through the door. "Audiences resemble the groups they come to see," says Wolf. Those words are reckless understatement.

No one who has ever mixed with a San Francisco psychedelic-style concert crowd is likely to forget the experience. Going to see the Boz Scaggs, Grace Slick or Hot Tuna? Better take ear muffs and a flak jacket. Psychedelic...