There are different ways to go about this. Do you choose a film that you love? Do you choose a really long film so you have less viewings before your time is up? Do you choose a comedy to help break the tension?
Thinking about it, I would choose "Fargo". I've seen that movie 20+ times and love every scene.
It counts... but I think being aroused for 24 hours a day for seven days straight and not being able to do, *ahem*, anything about it would be its own special kind of Hell.
i think i'd probably go with beyond the valley of the dolls. it's a perfect movie to me - it has everything. nazis, lesbians, hermaphrodites (spoiler, i guess).
the other option would be something really long, as you suggested. i've never seen the long cuts of fanny and alexander or love exposure. i think both of those run 6 hours. i don't think either would be good, though, cuz i definitely don't wanna read subtitles for an entire week. though maybe i'd start to pick up a little swedish?
ah, i should have looked it up first - the full length version is 5 hours. i believe that's the version that originally ran on swedish tv. i've only seen the 3 hour cut that was released theatrically. i've always wanted to go back and watch the full cut, but i end up thinking 'man, i could watch like three 80s slashers & have time to make dinner in between.'