I'm sure there are Classic Rock groups that you wish you could've seen in their prime.  For me Led is at the top of the list, followed by Hendrix and The Stones.  Of course we have our favorite hits from those legends, but wouldn't it be be cool if we could hop in the car with Marty and Einstein and travel Back to the Rock Future?  What group would do it for you?  Heart? ZZ Top?  The Beatles as they invaded the U.S.?