..I was about to suggest Moon and Sunshine, god damn it.
How about a terrible scifi comedy? Gentlemen Broncos.
Otherwise,
Forbidden Planet
Dark Star
Dune
Metropolis
Blade Runner
Planet of the Apes (original)
Children of Men
Akira (eastern, but still great)
The Day the Earth Stood Still (original)
Close Encounters of the Third Kind
Solaris
Total Recall
Invasion of the Body Snatchers
THX 1138
Westworld
Water World
Mad Max
Escape from New York
Minority Report
Gattaca
Fantastic Voyage
Rollerball (original)
Based on movies I've seen, not just ones I picked roaming through the internet.