From 1966 to 1975 were the glory years in my Rock world. I was fortunate enough to live in the NYC area and saw many of the Classics in their early days or at their peak.
Some of the shows were amazing, especially at the Fillmore East. Where else could you see The Allman Brothers playing in their first NY appearance opening for Blood, Sweat and Tears, or John Mayall with (if I remember correctly) Peter Green opening for Alvin Lee and Ten Years After! One of the best was The Electric Flag with Michael Bloomfield and Buddy Miles opening for Jimi Hendrix on his Electric LadyLand Tour. That show made you want to go home and burn your guitar!
Besides the combination of acts I was also fortunate enough to see Yes (1972), The Moody Blues (1970 and 1975), Led Zeppelin on their "Stairway to Heaven" Tour, Cream at MSG, Chicago at Carnagie Hall, Stevie Wonder opening for Three Dog Night, The Loving Spoonful opening for Poco (the original with Jim Messina and Richie Furay), Steppenwolf (my first concert in 1967, 6th row center) and CSNY. There are more, but I can't remember them all - what a time it was!