I just went to New York in late July and it was amazing
One place that some people over look is the restaurant 'serendipity' on 3rd stree/avenue?
it's the same restaurant that the movie "Serendipity" was based on.
The Ffrozzen Hot chocolates are to die for. But I reccomend you to not go during meal times. The line ups were hours long when we finished eating at around 5. Go in between meal times for the sundaes and drinks (and the food looks delicious). It's not horribly expensive either and the atmosphere inside is simply exquisite.
The toilets inside the restrooms are the ones where the water tank is a box above the toilet and you have to yank the chain to flush
Definately go see a Broadway show. I went and saw "Curtains" with the Tony award winning cast. it was fabulous.
New York Pizza in Little Italy is fabulous. So is shopping on Canal Street in Chinatown.
The subways seem frightening at first, but they are a great way for commuting around Manhatten.
Have fun