I need to correct my previous post -- I saw the Jimi Hendrix Experience with Mitchell twice in 1968, not 1967, but I am sure you all caught that error.  Hendrix first played the Winterland in early 68; his previous Bill Graham concert appearance was in June 1967 at the Fillmore, just after he played at Monterey. 

I should also add, I still have Keith Moon as the greatest rock drummer of that era.