I'll offer up four.
Springsteen at the L.A. forum for the Darkness at the Edge of Town tour. Record company seats, thanks to the fact my sister worked at A&M Records at the time.
Led Zeppelin at the Rose Palace in Pasadena, just after the second LP was released. Festival seating. Me and my girlfriend ooched our way to the front.
Berlin Philharmonic with Von Karajan at Pasadena's Ambassador Auditorium. Once again, record company seats. Transcendently beautiful tone.
Bizet's Carmen at the L.A. Music Center. I have no idea how I got them but Second Row toward the middle. Yeah, the performance was by the supposedly second-rate New York City Opera Company, but that didn't stop me from wallowing in the sheer beauty and excitement of it. The experience instantly transformed me into a complete opera fan.