If you are single - New York City, Philly, Atlantic City. If you are part of a couple, then Cape May in October is great. Princeton is good for like 2 minutes - hit the record exchange - its awesome.
If you are into fishing, you hit the jackpot - Fall Striped Bass run is just fantastic. Catch a party boat up around Sandy Hook, you'll catch as many 10-20 lb stripers as you want. Could even hook into a 50+ lb cow. Can fish them anywhere along the NJ coast in October; Sandy Hook area / Cape May rips are two of the best spots. Can catch them from the surf, if your not into the party boat scene. You can hit Island Beach State Park or any one of a number of surf locations that produce well.