Most people live in the UWS or Morningside Heights, ie pretty much between 70th and 120. The OCH is mostly between 110 and 120, so there are quite a few people living in that area, and the rest are living in self-arranged places further south.
I'd say about 60-70% of the class lives in that area. The rest live throughout Manhattan (mostly people who lived here before) and a few brave souls in outer boroughs (or worse). If you live by the 2/3 express stops at 72 and 96 you can jet downtown pretty quickly. I live near 96 and its a pretty good location for getting around -- you can get onto the 1 for quick access to campus and on the 2/3 to jet pretty much anywhere downtown.
LMK if you want to chat further about locations. If you're looking for roomies, whenever they get the Class of 2014 Facebook group going I'd use that as a resource to help meet people. I know quite a few people who found their roomies that way. GL and welcome to CBS!!!