I've been to a few concerts in my life, so I've seen a few bands that I haven't heard of, a few that stick out :
Aug 18, 1983 - I went to see Y&T open for Sammy Hagar at the Fairgrounds in Sacramento, CA. The opening act at one point said to the crowd "We were personally invited to play for you today by Mr Hagar, so if you are booing myself and my band, you are booing Mr Hagar." Then Stevie Ray Vaughn ripped into one of the greatest guitar solos I have ever had the honor of hearing. And, for the record, neither myself nor my buddy Walt had been booing.
Nov 17, 1986 - not exactly the opening act but... my girlfriend worked at The Stone in San Francisco, I was between tours so I stayed with her for a week, going to with her to the club every night. That night it was Stanley Clarke, supported by Jeffo. At one point early in the evening, a little drunk guy stumbled over to me for the sole purpose of explaining to me that I was wearing shorts and that it was quite cold outside. I told him that's why I was inside, instead of being outside. He though about that for a few seconds, then said "good point" and stumbled back into the crowd. Late in Stanley Clarke's (excellent) set he said to the crowd "I would like to introduce to you a friend of mine, ladies and gentleman, Mr Jaco Pastorius" at which point that little drunk guy performed the greatest bass solo I ever witnessed (note that I toured with Talas, and saw Cliff Burton perform "Anesthesia (Pulling Teeth)" a number of times, including on that same stage).
Summer 2003 - I was the tour manager / tour accountant for the Warped Tour, a tour that had 568 people on the Canadian immigration paperwork (and that's the people who CAN cross the border), so I tended to be quite busy on an average day, not as much time to watch bands as I would have liked. A couple shows into the 45 date tour, one of the stage guys came into my corner of the production tent, and said "you HAVE to come checkout a band that's on my stage this year". I thanked him for alerting me, but told him it was never going to happen, since the schedule of bands changes every day, I was never going to be able to get out to see them, unless he sent somebody to drag me out moments before they played, because I didn't have time to hang out at a stage, as much as I might enjoy it. A couple hours later he came back, grabbed me by the arm, told the tour manager that I was about to pay to come back in 30 minutes and we hustled over to see S.T.U.N. for what is still one of my favorite live sets I have ever seen. After that, I had one of the production assistants tell me when they were 5 minutes away from going on stage, and where their stage was located, and I saw them probably 30 / 35 more times on the tour.
https://www.chron.com/entertainment/...ur-2128642.php
https://www.youtube.com/channel/UCPB...b9eHQ/featured
https://en.wikipedia.org/wiki/S.T.U.N._(band)
November 19, 2014 - I was doing a few shows with Jane's Addiction and was by the side of the stage as the support act were going on at the Ogden Theater in Denver, because I wanted to make sure they ran on time. On walked the drummer, on walked the bass player. Where's the rest of the f'n band I said to the local stage manager? That's all of them he told me. Wow. What a band. I made sure to watch them at the two other shows they opened for in Las Vegas that weekend. I've seen them a few more times since then, and they are still great.
https://en.wikipedia.org/wiki/In_the_Whale
July 26-27-28, 2016 - I took a quick vacation to visit the Warped tour and after being told "make sure you see them" in Milwaukee, I also made sure to see them in St Louis and Kansas City - The Interrupters. I was bummed that they didn't get a chance to tour this summer with Green Day, but I'm sure they will be back once the zombie apocalypse is over.
https://wearetheinterrupters.com/