Ones that I had an opportunity to see but didn't ...

Pink Floyd
Santana
Willie Nelson
Johnny Cash (major regrets here )
Steely Dan
The Who
Miles Davis
Van Morrison
U2
Elvis Costello
Pretenders
Crosby Still Nash Young
Frank Zappa
Dire Straits
Eric Burdon

There's also one particular Neil Young concert I missed, also a Jeff Beck, but I've seen both these guys many times.

That's all I can think of for now.