I’m basing my answer on the horror genre, cuz that’s the only thing I know stuff bouts;
I strongly agree with the idea of good, legit suspense, well fleshed out characters and an interesting interaction between them at all times.
I might also suggest the following; the place in which the movie takes place needs to be a character in its own way. I mean that the location must be interesting in itself, even if it’s as such for the mere reason of complimenting the events that strike it. Depending on what the movie is doing, the location needs to respect that. In Paranormal Activity, they offered a nice big apartment with all sorts of nooks and crannies that were creepy just by being there. (a modern apartment that’s freaking me out; this is a rare feat indeed) Even if nothing happened with them, (nooks and crannies) the entity in the movie made absolutely no guarantee, so the whole apartment was scary, and I found myself worrying and being all edged out on places in there that, finally, had dick all to do with anything. The movie messed with my ass, because the location had a personality.
Blair Witch had very normal looking woods, which helped with the realism that movie was going for.
Rec uses an old style apartment building with narrow halls, shitloads of stairs and labyrinthy rooms in order to accentuate the feel of panic as zombies go after people. It also uses a lot of darkness, which is, for once, actually not annoying at all.
The place needs to be built to accommodate its premise, especially if a movie mostly takes place in the one location.