At first glance, looking at a classic SciFi film from the mid 70s might reveal a slightly tongue in cheek campiness and very little else. Logan's Run is a good example of something that might seem rather dated and silly, but has a lot of metaphorical layers to it. These layers connected with me as a young person and this film and its central themes stayed with me.
If you don't know the premise, it is essentially this:
In a post apocalyptic world, a domed city thrives with a population of beautiful, care-free people run by a central computer network. No one has to work - leisure and pleasure abound, but there is one catch: when you reach your thirtieth birthday, you must be "renewed" in Carousel. Carousel is a public spectacle where those whose "life clocks" have expired must rise to the top of the amphitheater to be obliterated by a lethal machine. The throng of spectators cheer because there is a rebirth promised to all who renew.