I find that a big part of the reason I enjoy a particular movie is the setting. For instance, right now I’m watching Desk Set starring Hepburn and Tracy, which deals with the installation of a large computerized reference system in the headquarters of a national TV network. The dramatic elements are rather standard fare–the love triangle between Gig Young, Katharine Hepburn, and Spencer Tracy, the last two of which gradually fall in love as the movie progresses. For some reason I’m fascinated by early computers (the movie was made in 1957), and also by 1950’s corporate life. So this movie gets me every time. If the movie had the same dramatic devices but took place among, let’s say, lumberjacks in the Pacific Northwest, I wouldn’t give it a minute of my time. My reaction to Titanic is similar. It’s generally regarded as a “chick” movie, but I find myself strongly attracted to it because the underlying premise of gradual doom is so compelling.
What about you? Can you forgive weak acting or plot if the setting of a movie interests you?
For some reason I know I’m going to like a movie if the setting is an asylum or the context that of mental instability/disability.
I enjoyed Beautiful Mind because of the Schizophrenia. I’ve enjoyed many films set in asylums (most recently Girl Interrupted)
Human behaviour can fascinate me, and for some reason it’s even more fascinating when it’s malfunctioning. I sometimes wonder what if I’d pursued a career in psychology rather than computing.
I have no idea why, but I am crazy about movies with lots of panoramic desert views. “Lawrence of Arabia” was the first movie I can recall seeing that stirred this love of the desert. Recently “Hidalgo” touched the same emotional hot spot.
I have never visited a desert, and it’s likely that I never will. But it seems that something deep inside me wants to be one of the Sand People.
Films set in European cities or New York City. I love The Talented Mr. Ripley for it’s Italian theme (for other reasons too, but without the Italy thing, it wouldn’t be nearly as high up on my list).
There’s also something about movies that were made in the early 70’s - e.g. The Godfather, Harold & Maude - they have this certain sort of grainy film over them, which for some reason appeals to me. 
Also, films involving train travel. Most memorable is the train scene in North by Northwest, when Cary Grant is sort of half-making-out with Eva Marie Saint… good lord! Sexysexysexy…
The English countryside. I’m probably the only person I know who actually enjoyed The Englishman Who Went Up a Hill But Came Down a Mountain. Since there are a ton of movies set in the English countryside, it appears that I don’t have any taste. At all. But I do . . . just not when it comes to these movies.
You realize, of course, that The Englishman took place in the Welsh countryside, not the English countryside. It was rather a major plot point. And you’re not the only one to like that movie.
Argh. Yes. Make that Great Britain and chalk another one up to an ignorant American.