One movie which well describes the '50s is James Bridges'
September 30, 1955 starring Richard Thomas and detailing the effect the death of James Dean has on a young man and his friends. It's interesting to look at the 1950s from a 1970s perspective, especially since the film is basically autobiographical.
Others I enjoy about the '50s include all the music biographies of the time, including
The Buddy Holly Story, La Bamba, Coal Miner's Daughter, Great Balls of Fire!, American Hot Wax, etc. You've also got cool movies like
Diner, which shows the transition of boys to men and the '50s to the '60s, and
Blackboard Jungle, which even if hokey in some ways, still seems pertinent to today's school and youth.
This topic is extremely huge, so I'll wait for you to comment before I go into other things such as the Cold War, McCarthyism, Space Exploration and Aliens from Outer Space, Foreign Films, etc.
"Naked Woman, Naked Man
Where did you get that nice sun tan?"