I still cringe when I realise that of my 5 favourite films of all time, I've only seen two on the big screen (2001: A Space Odyssey & Star Wars).
The Godfather, Chinatown & Yojimbo - best I've seen is DVD, and for years it was just good old fashioned nasty pan & scan VHS.

Says a lot for the films that their brilliance can still shine through when displayed in such a mangled format.

Sad thing is, over 20 years ago, a Sydney cinema had a GFI + GFII double on (Part III was about to be released, I think, or was just out), but I couldn't go - the R rating in Australia meant no one under 18 could go in, even with a parent (I was only 15).
Back then, The Godfather still had an R-rating in Australia, the equivalent of a US NC-17, although Part II had an M-rating (sort of halfway between the US PG-13 & R).
My folks were happy to get the videos for me from the store (and watch them with me), but a seven-hour cinema sitting was always going to be a big ask, so I didn't bother.