If you're sailing out of NYC the cost of parking may be more than the cruise.
Last visit we stayed at Crowne Plaza Time Sq. , before that Marriott Time Square. Both excellent hotels, and great locations, about a 5 min. taxi ride to the pier.
.. yes.. I just called Carnival and its $30/day to park at the pier.. its an 8 day cruise, so we are looking at $240.00 for the duration.. and then we are looking at 2 hotel nights.. one before the cruise, and one after.. so thats another $250.00 or higher.. but even at $490.00 total, its still cheaper than airfare for a family of 4.. we're "only" 14 hrs drive from here to Manhattan.. figure if we leave by 6am here, and all our pitstops included, we'd be in Manhattan roughly 10pm..