The Bikecentennial organization morphed into being Adventure Cycling Association. They have a forum and have dedicated a section to that first summer of rides in 1976. I'm sure they'd love to hear from you folks that posted and you could find posts from others that were on those rides.
http://www.adventurecycling.org/foru...php?board=29.0

I was 15 that summer, but I couldn't scrape up the funds and probably wouldn't have gotten my parents permission to go. I did hold on to the dream, though, and finally rode coast to coast last year at the age of 49.