Not sure what type of service you are looking for (private car, public van, etc), but when visiting NYC we always take either the Super Shuttle (www.supershuttle.com) or Airlink (www.goairlinkshuttle.com). Small vans that will give round trip service with drop off and pick up at hotel at times that can be flexible for you (if flights are early/late, etc.). A round trip can also be booked into one airport and out of another. Prices are very reasonable. Hope this helps.