Other than the train, there is also an express bus from South Brunswick. My neighbor has been commuting to mid-town for years taking the express bus. He would not take the train since he would sleep on the train and the train may take him back to Princeton, or further to PA.....
When I worked in NYC, I always took the train. If you get there before 7AM, parking should not be a problem....
There are a couple of choices. You can drive to the Bridgewater station and take a train from there. Itis a slower diesel and you have to change in Newark. You can drve to Princeton Jct or Jersey Ave New Brunswick and take the high speed line. Or drive to Someset and take a bus. And of course there is drive to Jersey City and take the Path from there. Here is a good link to NJ Transit http://www.njtransit.com/sf/sf_servlet.srv?hdnPageAction=TrainTo
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