which is the best airport for a day trip to NY? times square, central park, Manhattan?

If I want a relatively quick and easy shot into Manhattan, then I prefer to fly into Newark because we just easily take the train right in.  But I don't think a day trip into NYC from any airport is particularly reasonable.  

http://www.nycsubwayguide.com/subway/airports.aspx

Day trip?? Sounds like you intend to fly in, stay for a couple of hours, then leave!  Neither JFK or LGA are close - they are in Queens, and expect the traffic to be hideous.  Newark is not going to help you much either.  There is nothing to DO in the park or Times Square - except gawk at the lights and other tourists, or stroll around (forgive Park fans - but there are FAR more interesting things for a newcomer to see and do!).  To come here and breeze in and out is a waste of your time.  We do not live far away - less than 2 hours - and so are there often - going to be there on music business tomorrow.  Were there a couple of weeks ago for the MET.  Will be there in a couple of weeks for MOMA.  Then Back to MET when musical instruments new exhibit opens in March.  Friend from  Catalunia might be here in March - wants to see a show, so we will take him.  But if you want to do multiple things, you really cannot just zip in and out.  We do - but we LIVE HERE - no big deal, and we have gone hundreds of times.  If you are going to be here longer - then let us know, and we can give you OUR favorites - do not know what you like,