In Memoriam, FlyerTalk Evangelist
Join Date: Jun 2000
Location: Benicia CA
Programs: Alaska MVP Gold 75K, AA 3.8MM, UA 1.1MM, enjoying the retired life
Posts: 31,849
Sure it's possible, and if you're that close well worth the trip in. I've done a number of one day visits, in at 7a.m., and flying back out at 5pm. If you check previous threads in the NYC forum they will cover the various transit options and costs (subway, Long Island RR, AirTrain).
If you go in by AirTrain and subway (that's how I go in), allow about an hour to get into Manhattan. If you go by AirTrain and LIRR, less. You can get an all-day subway pass and really pack a lot of things in, from Battery Park up through Central Park. I'd start working on a list of places you want to see.