In the early days, Nirvana used to play a lot of benefit shows, and I saw them then, but didn't count it because it was usually a three song set and you were done.
You would have to be over 30 (I think) because a lot of the early Nirvana shows were 18 and over. Sublime I would have said the same thing, except they did a warped tour gig that was all ages.
Blind Melon was just luck. I wanted to see Neil Young and STP, and they happened to be the third band on the ticket. I did get a beer thrown at me by a Neil Young fan for enjoying an opener - only time that's ever happened to me.