What Is And What Should Never Be - Led Zeppelin
People often say great things about Page, Plant and Bonham, but not as often about John Paul Jones who IMO is one of the best bass players in Rock n Roll music. (Right behind Bapu of course)
The Great Gig In The Sky - Pink Floyd
I absolutely love Clare Torry's improvised vocals on this song. At the time I wanted to transcribe it and play it on saxophone, but the rest of the band I was in didn't want to do it.