When we were there in 2004 for National AIFD, There was a fantastic shop I visited on the corner of Lexington avenue....I think It was on the same street as the back entrance of the Waldorf Astoria. The shop name is called Bloom.
Also, In the underground mall area of Rockefeller center was a gorgeous shop that had all their flowers and displays like you would find in a typical holland shop.
Also, There is a very old and established shop in Rockefeller center as well .....The shop dates back to the late 1800's/ early 1900's. Irene Hayes, Wadley, Smythe, and LeMoult. In fact, if memory serves me right, I seem to remember reading that Adolph LeMoult of that shop was one of the original founders of FTD.
Hope this gives you some points to think about.