I live in NJ, but my work territory includes the metro NY area. I frequently have the joy of driving in and out of the city during peak commute times.
Restaurants, clubs, etc. will be busier on Friday, so if there are particular places you want to go that require reservations or may involve a wait, Monday might be better. If you are a football fan, the Superbowl may factor into your decision too.
There was already a Superbowl watch party mentioned, not sure where it stands though.