Well, since we're talking about concerts, there are two that stay etched in my mind:
The Alice Cooper concert I mentioned above; they did a good part of the Killer and Love It to Death albums and I recall one of my favorite magicians at the time, James (The Amazing) Randi, played the dentist in one of the songs, complete with the whirring drill. It ended with Cooper being decapitated by a guillotine (what a way to avoid encores, but it was around 3 hours long). But like Sue, I have difficulty in remembering the young lady I attended with (probably for good reason, but I'm not sure).
A David Bowie concert at Radio City, right after he released Space Oddity (around 1972). I recall that I've never quite seen (or heard) anything like it before (or since). Some of the songs performed remain with me to this day.
Edited to add: I checked online and the concert was Valentine's Day 1973.