A few times a month, Sam Satenstein lines up outside Terrapin Crossroads, a music hall and restaurant in San Rafael, Calif., for performances by the band Phil Lesh and Friends. The hall is owned by Mr. Lesh, the 75-year-old Grateful Dead bassist, and his wife, Jill. Mr. Satenstein is almost always first in line; when the doors open he rushes in to secure a spot on the side of the stage favored by Mr. Lesh. He plops down on the floor to protect the space.

“You can feel Phil’s giant bass when you’re standing up there, so I try to get that spot right up at the front,” said Mr. Satenstein, a 32-year-old online retailer who sells vape pens and lives a couple of miles from the hall. As soon as the band starts, Mr. Satenstein and others let loose, bobbing their heads and grooving to meandering renditions of Grateful Dead songs.