Luckily, being from the UK, I got to see Led Zep in January 1973 at a local concert venue which probably held less than 2,000 (before the days of arenas). I was still at school at the time. Saw them again in 1979 at Knebworth with 100k others, just before Bonzo's passing.
As with some other posters, never got to see Pink Floyd back in the day, turned down a chance to see The Wall at Wembley in 1980 - doh!