The scene in the closing theme where Ann flies her kite on the pier is actually the Downtown Manhattan Heliport at Pier Six in the South Ferry section of Manhattan.
http://www.downtownmanhattanheliport.com/index.html

Just thought some of you would like to know, if you didn't already.

More details.

https://en.wikipedia.org/wiki/Downtown_Manhattan_Heliport

http://wirednewyork.com/forum/showthread.php?t=19323

Well, what do you know? I found an older thread about this;
https://www.sitcomsonline.com/boards/showthread.php?t=191069