As far as Chicago goes,there's a really good concert from them on YouTube from Tanglewood (Lenox Ma.) in 1970. I would have loved to seen this show! They definitely had some nads!
Here's a link to listen to 25 or 6 to 4:
https://www.youtube.com/watch?v=7uAUoz7jimg
Here a link to listen to the whole Chicago concert:
https://www.youtube.com/watch?v=_oAoSZ2y1cw