Liberty Harbor works very well. The camping facilities are minimal and it is expensive but the location is great. Nice view of the city and Statue of Liberty. It's a very short walk to the train station (office staff provides details) which takes you to the 9/11 museum in minutes, or on weekdays there is comuter ferry service also into the city (Wall Street area) which is a pleasant ride, if you stay elsewhere, you'll have a very long ride in.