Thanks everyone for including your experiences in this thread. I'm a native New Yorker who lives in Maryland and I will be taking AMTrak to NY for a cruise Sunday, September 1 this year. I will not be checking my bag, I want my belongings near me and tend to not overpack for cruises.
Good to know it is best to take the escalator (which I hope will be working) locate the taxi stand. I arrive at 10:30 with a 1:00 check in. Since it will be a holiday weekend, hopefully Manhattan will not be too busy!