The ride on Metro North to Poughkeepsie is really something. If you have the time definitely check it out.
My top recommendation is to take a ride on the R32 subway cars on the C and J lines. These are mid-1960s Budd products. The Budd fluting is very apparent. The cars are scheduled to be withdrawn from service in 2019 if not sooner, but if 53 year old subway cars peak your interest they're worth a ride. They're some of the few cars in the fleet that afford a view out the front window and much of their run on the J is elevated.
Down in Bay Ride, it's not really accessible for photographs, but you can still observe car float operations between Brooklyn and Jersey done by NYNY Rail. New York & Atlantic Railway brings cars to them on their Bay Ridge Branch. You can also check out NYAR on their Bushwick Branch, both of which run out of their yard off the Fresh Pond/Metropolitan Ave M train stops in Queens.
Lastly, about 10 minutes past the George Washington Bridge in New Jersey is the NYS&W and CSX Riverline. The station off Mount Vernon St in Ridgefield Park offers views of both mains, and Industrial Avenue will bring you right by the NYS&W fuel pad. Road trains with solid sets of yellow/black SD60s and SD40-2T tunnel motors run Monday-Wednesday-Friday in the afternoon.
