In film it really comes down to what type you like or what strikes you in a film.
There are many great films that deserve a second or third viewing, some just because of their quality, others because the speak to you.
For me:
The Sting.
One because it was a great film, two it had a great cast, three it had a great score, and four it has a nice twist.
Citizen Kane.
Again a great film by a young film master in the making. Many things done in this film were groundbreaking in cinema, the use of story, the style of scene shots.
A film studied today in film schools all over. Worth seeing more than once.
Casa Blanca.
Great cast, great locale, and at its basic core it asks existential questions to be considered.
Young Frankenstein.
Again from a great film maker.
So many things are going on more than one viewing is required, it has running gags, sight gags, double entendres, you name it, it has it.
Which leads me to the next film.
Airplane.
For the sheer number of jokes, puns, running gags, sight gags, double entendres, satire, again you name it had it. So un-PC I doubt it can be made today.
Dr. Strangelove. Again so much going on you need to see it more than once to get it.
A great cast, a score you can not forget, and inside jokes, or are theu just dark humor?
Real fears at the time about living another day, or not.
Major (King) Kong, General Jack D. Ripper. Col ‘Bat’ Guano. You have to love it.
In Sci Fi:
Forbidden Planet.
I my opinion a great 50’s Sci Fi film.
Cheesy effects and scenery by today's standards, but good for the time.
Plus suspense, action, and more than a bit of existential thinking thrown in.
2001: A Space Odyssey, a master work by a master film maker.
A great score.
Great special effects even by today's standards.
And it asks the basic questions, why are we here? Are we alone?
In westerns I am partial to the 60’s:
Once Upon a Time in the West. Great cast, great visuals, great score.
The Good the Bad and the Ugly. Again great cast, great visuals, great score.
Also High Noon
Also Stagecoach, 1939
In foreign film I would say you need to see these more than once.
Seven Samurai, by the great and I mean GREAT, Akira Kurosawa film maker.
Another film studied today around the world.
Also from Kurosawa. Roshomon, and Sanjuro
Someone already mentioned the TV show:
Babylon 5
In my opinion the best thought out, and thought provoking TV series made so far.
If I thought about it, and drank on it, some more, I am sure I can come up with more worthy films, but this will do for now.