For NYC there is not many airfields with easy access to the city that don't charge $$$ for 100LL
23N does look cool, but I have never been there. Not sure what the condition of the field is, and it is pretty far into the city from there...
N07 is another really cool airfield in Jersey, nice resteraunt on field, small airport feel etc. However, I don't think there is a really good way to get from there to the city easily.
CDW has pretty high parking/landing fees
MMU has some fees but the FBOs are definitely the $6+/gal crowd
HPN is busy but not as bad as the other Class Ds around but you would have to rent a car or get to the train station to get to the city which is probably 1-1.5 hrs to get to the city from there...
Honestly even if you were willing to pay the fee$ short of flying directly into JFK there really isn't an easy or fast way to get in the city from any airport around NYC that I'm aware of.
Coming from New England if I am going to the city I usually just drive, its easier/faster than flying in unfortunately.