Heavy Rain.
Not going to be spending much time on games this month and all indicators seem to hint that the best experience for that title will be on the first play through since it's heavy on narrative and essentially a mystery story.
I can always pick up Bioshock 2 for PC later. If I see a ridiculous deal for the game on either PS3 or Xbox (still assuming the Xbox version will be slightly better than the PS3), I may just pick it up for console first. If it's as good as the first one, I'll be playing both this month regardless of time constraints.