A few cautions to be wary about...I speak from experience.
Be very careful if you are taking the viper. Manhattan has so many *** holes, and with the viper, not only will you feel all of them, your suspension is going to take one hell of a beating if your not careful to avoid the big ones.
Park the car only in an enclosed guarded parking lot. Don't let the attendant park your car and only park there if you can pick the parking slot. You see, these places pack them in extremely tight and there are many many stories of dings and dents after parking at one of these locations. The alternative is to park it on the street and risk having people scratch it with their shopping bags, purses, hands (after wanting to touch it), or other cars banging into yours because they can't park themselves or don't care. Parking is tight in the city and people will squeeze in in front of you, behind you or beside you, like you wouldn't beleive.
Drive defensively and be very careful; you will get cut off by a 3 taxi cabs per block. You must watch out for kamacazi bike couriers, middle of street pedestrians crossing the street all over the place, and drivers swinging their doors open after they have parked their own filthy cars in the middle of the street.
Most folks in the city aren't really car lovers and you will find that the majority of them will show your car little respect so be careful.
Other than the above you should be alright.
As far as things to do. Go to a few of the museums (metropolitan museum of art or natural history to start), see a broadway show, take a walk through central park (only during the day though), eat a 'hot dog cart' hot dog, have a slice of cheese pizza, and eat your ass off at some of the best restaurants in the world. If your downtown take the ferry to the statue of liberty, if your midtown go atop the empire state building, if your on the west side take the circle liner around manhattan island. There is lots and lots to do.
New York is a nice place to visit. Visit being the key word.
(5k miles) "Tatorized"
