Concerts and school
I started attending concerts in 1976, I was 16 years old. We would skip school to go and nothing was said by the school principal until 1978 when he suspended us for taking the afternoon off from school. It was well worth it though, the concert we were suspended for attending was Emerson Lake and Palmer.

Some great bands
In no particular order, I'm going to try to remember all of the bands that I've seen.
Uriah Heep, I saw them twice. The first time I saw them, Ken Hensley, the keyboard player had a joint hanging from his mouth the whole concert. The second time I saw them David Byron the original lead singer was gone and John Lawton was the vocalist. Lawton was an ill fit for the band and in my opinion they sucked.
Blue Oyster Cult was awesome and they were debuting the laser light show. The laser lights were OK but not great. I still remember them playing "The Last Days of May", which is one of my all-time favorite songs ever.
Rush opened for BOC that night. Everyone around me said Rush was going to blow BOC out of the water, Rush was good but Blue Oyster Cult were still the headliners.
Jefferson Starship. Without Grace Slick but Mickey Thomas was fantastic. I think he had one of the best rock voices of his time. Starship put on a heck of a show.
America. Not the heavy rockers like most of the other bands I've seen but nonetheless they were very good. "Horse With No Name" is still one of my favorite songs and to hear them play it live was quite a treat.
Lake. A quite talented band from Germany. We had never heard of them at the time and I really don't remember much of the concert but apparently they left quite a good impression on me as I did purchase three of their records on vinyl and then later on, the same three on CD.

Black Oak Arkansas. Jim Dandy Mangrum was quite the showman, they even played "Jim Dandy to the Rescue" with Ruby Starr. Mangrum had a voice you'd never forget. I still like to listen to them and "Street Party" is one of my favorite albums. 
Ted Nugent. I wish I could say I actually "saw" Ted but I partied so hard before and during the concert I had to leave the arena and go get sick in the parking lot. I heard the whole show but never saw Ted at all.
Nazareth opened for Nugent that night. They were quite mediocre. Some bands just don't play live well at all.
Skyhook, I really don't remember them at all, these were party days folks. Brownsville Station was fantastic. During the song "Smokin' in the Boys Room' they asked the audience if anyone had anything to smoke, the audience proceeded to throw about 30 joints onto the stage. True story!
Kiss. "You wanted the best and you got it, the hottest band in the land, Kiss!!!" Wow, what a show! No other band that I saw put on a such a visually intense show as Kiss. The pyrotechnics were outstanding. I saw them on the "Destroyer" tour. They opened with "Detroit Rock City". Kiss was by far the best visual and most energized concert I've ever seen. Paul Stanley still sounds nearly as good today as he did back them, which is incredible, most vocalists lose their range as they get older but not Paul.

Sammy Hagar was phenomenol. I've never seen anyone run so much during a concert as Sammy did. He had to be in great physical condition. He had a huge circular mesh platform that went out about 40 feet out and over the audience, Sammy ran around this platform non-stop the whole show, it really was amazing.
Emerson Lake and Palmer. They were undoubtedtly the best concert I've ever seen. No warm-up bands, just ELP for three hours with a 20 minute break in the middle. I can't even describe how great they were, I still get goosebumps every time I think about it. They didn't even play on stage, they were on the floor of the arena and brightly lit, they were true showmen. And the audience was so enthralled and obedient, no screaming, no yelling, no rowdiness. Everyone sat/stood and listened until the last note of each and every song and then they clapped, it was like watching an orchestra performance. The absolute best show ever, and of course I was in the front row!
Ozzy Osbourne. I saw Ozzy in 1981 during the "Diary of a Madman" tour. It was unfortunately one of the last concerts Randy Rhoads ever played. Randy's death was so senseless and he truly was one of the greatest and most influential guitarists of his time, I couldn't take my eyes off of him the entire concert. It was spellbinding to watch him.