If you decide to stay in NYC and not take another overnight trip, I believe you can go up the Hudson Valley on a few different bus or train trips.

NYC to Connecticut, a town such as Greenwich, that would be nice. Easy to do in one day by train back and forth.

NYC to West Point is a terrific option.

Up the Hudson from NYC by boat might be available. That could be a fantastic daytrip.

Looking at the cliffs of New Jersey on the NJ side of the Hudson, seeing the beautiful fall colors, that is exquisite.

Bear Mt State Park (my daughter lives very near one of the park's boundaries) is utterly gorgeous in Autumn. But maybe hard to get to without a car.

If you are tempted, the nearby town of Warwick has the most beautiful farmer's market and it is great in October. You could drive there and back in one day, taking in Warwick, Bear Mt, and maybe more. Very lovely Autumn scenery, and a "New England" feel.

I think Gray Line of New York does a day trip by bus to West Point, which is totally gorgeous.

Also look up the Hudson Line out of Grand Central which seems to stop at a number of great locations.

tigerboys: I have a book marked thread from another board. I dont think it is ok to post it on Fodor's so if you are serious about day trips on public transportation, you can email me at tuscan life edit 2002 at yahoo dot com (remove spaces).