There is a brilliant book on Pan-Am, called "Skygods" written by Robert Gandt.
To me memories of Pan-Am are, that these guys were top aviators, at least the IGS (internal German Service) ones. My father has had close contact with them as an ATCO at Munich and Stuttgart in the sixties, seventies and eighties. One of the last times I saw a Clipper, was a B727 over the Weidacher Hill (NDB approach 08, EDDS) in an almighty sideslip, out of the sun. I was sitting in a C150 for a solo student flight...shortly afterwards they were history...