Two shows that featured a variety of performers.
Tom Petty, Shoreline Amphitheater, October 13, 1986. No Heartbreakers, just Petty solo. This was the first annual Bridge School Benefit, which ran from 1986 to 2016. I admit at the time, we thought Petty was drunk, but watching the video now, it seems we were blinded by the fact that we were waiting for Bruce Springsteen.
Guided by Voices, Greek Theater, 7-2-99. It was called "This Is Not a Festival", and was headlined by Sonic Youth. I was there to see Sleater-Kinney. Guided by Voices had (and have) a substantial cult following, and they are extremely prolific ... by the time we saw them in 1999, they were about to release their 12th album, and they'd also already released 11 EPs and a bunch of singles. I don't have much to say about them, positive or negative. Here's "Teenage FBI":