I was at that concert. The opening band was Taste (Rory Gallagher), next was Delaney,Bonnie and Friends (Dave Mason on guitar), Blind Faith. IIRC - Chip Monck was the MC, replete in Orange,suede suit. My friend and I climbed the fence that night to get in. ;-) . Your recollection of Janis(along with Sam Andrew) being there is correct as she sat near us on the ground in front of the stage. Three things that stand out about BF are that Ginger was playing the same kit that he had when they(Cream) played Oakdale,Winwood played a turqoise/foam green Firebird,same color as the Strat he has today and BF seemed to be his "backup"band.

I saw them at MSG and remember that Free was the opening act. My most vivid memory is that I stepped forward to snap a few instamatic photo and got plunked on the head  with a batan by some gung ho NYC copper! The best part was that Ginger rushed to my rescue and starting beating the copper with his sticks! I got some great close ups of Clapton right before all the excitement and the pictures are hanging on my wall to this day Man its great to be in my fifties and have memories like  these! Hope they come to LA so I can see Clapton and Winwood together again and what's with Clapton bringing this show and the Cream show only to NewYork? I never should of moved to California!

Peace