I am not a local to New York and have actually only been a couple times (I love it!), but I wanted to also endorse the red double-decker buses.

My sister and I were there in November last year and we bought the 48-hour pass and used it as a taxi service, basically. We could get on and off where we liked and we got great information as we went. We thought it was well worth the money.

Enjoy! Tiffany, California