Glad to see the Glengarry love. I've watched that movie maybe more than any other. Does Night of the Living Dead count? Maybe not, but the best part of that movie is the claustrophobic feeling inside that living room.
now yes. it does take place primarily in four rooms. But each room/chapter is it's own story...and each ruelz.
especially the part where "....there's room 309, there's this scary Mexican gangster dude poking his finger in my chest. There's his hooligan kids snapping their fingers at me. There's a putrid, rotting corpse of a dead whore stuck in the springs of the bed. There's rooms blazing afire. There's a big fat needle from God knows where, stuck in my leg, infecting me with God knows what. And finally there's me, walking out the door, right fucking now. Buenas noches. "
Deterrence (1999) - While on the 2008 election campaign trail, the sitting President, who through unusual circumstances, was not elected to his position, finds himself and several advisers stranded at a diner during a snowstorm. While he's there an international crisis takes place and he finds himself grappling with the decision of whether or not to use nuclear weapons. This political thriller doesn't entirely work, but it's certainly interesting, has some interesting twists right up until the very end of the film, and is well worth watching.
Secret Honor (1984) - Based on a one-man play, this Altman film stars Phillip Baker Hall as Richard Nixon, sitting in his office with a tape recorder and delivering a monologue about his career for a solid hour and a half. This is far more interesting than it sounds; Hall delivers an amazing performance and the script acts as a sort of fictional (one hopes) secret history of the Nixon years.
Not a movie, but I liked how each episode of the show Tidus pretty much took place in one room or area. The flashbacks and narration were on separate sets, but the main story always stayed confined to one set. It kinda felt like you were watching a play, instead of a sitcom.