Hi...we will be coming from JFK into grand central station to take a metro north train up to Poughkeepsie. It will be a Tuesday afternoon, between 11:30 and 12:30pm. I am wondering if I should buy the Metro North train tickets ahead of time or just get them when we arrive to Grand Central. I would like to minimize on time spent at Grand Central when departing...we will be able to explore and look around when we come back from our few days in the Catskills. We only have a very limited time in the Catskills (two half days and one full) so if anybody has any faster suggestions as to how to get there (woodstock, tannersville, round top areas) please lmk. The price of a rental from JFK was much more expensive then getting to grand central, metro north and renting a car in Poughkeepsie. Thanks so much for any advice.