I've taken the cruise this July, and had the same question. Before you start hitting people up for favors or going w/ a van service that will easily be >$75 each way plus tolls, park in the garage right there.
Drop everyone and the luggage off first and then go around and up to the top and park the car. You have to pay upfront about 180 and then park yourself.
super easy, and you're not waitng for rides on the way back....I got out of there supper fast, and you're right by the lincoln tunnel.
the good doctor