Due to a need to stay in New York City this summer, near the Plaza
Hotel, and due to parking being very expensive, was wondering if your
experts could point out the least expensive overnight parking
facilities in Manhattan, closest to the Plaza Hotel. The period of
time will be about 2 months so long-term passes will hopefully be
acquired. But the overall theme should be the cheaper the better.

I was recently in Manhatten, and was able to find street parking.
You'll have to move your car once or twice a week, though.

Our original plan was to park in New Jersey, and take the PATH train
in. New Jersey parking is very reasonable, but you won't have use of
your car. Driving is horrible in Manhatten, and even if you think you
can handle it, I don't suggest it. Add on the bridge and tunnel tolls
every time you turn around, and you are better off in New Jersey.

Enjoy your visit-
  Anne

Other researchers may want to view this question; 
http://answers.google.com/answers/main?cmd=threadview&id=213646 
before answering, for an understanding of the customer's idea of a complete answer.

Parking around the Plaza will no doubt be at a premium.  You might
check Icon Parking for a monthly quote.  I believe Pier 40 is one of
the cheapest long-term parking situations in Manhattan but it would be
quite a hike downtown.

http://www.iconparking.com
http://www.pier40.cc

Good luck,
V