Side trips from NYC during August
 

My sisters and I will be staying in NYC from Aug. 8-17 and would like to rent a car and spend maybe 13-16 driving, returning to NYC for our flight back to CA. Any suggestions or recommendations?

Drive up the Hudson Valley to the Berkshires in western Massachusetts.

Howard's suggestion is good. You can also do a Philly/Bucks County combined trip in the amount of time you have. Museums, antiquing in New Hope and Lambertville, walking along the Delaware River; a great way to combine another Northeast city along with some country sites.

Can check out the Jersey Shore. Head to Wildwood for a pretty beach

For a beach/social environment, try the Hamptons. <BR><BR>I'd recommend somewhere further out like Montauk or Ammagansett. There are several nice towns for browsing, dining, etc. They include Southampton, Sag Harbor, Easthampton. <BR><BR>However, the Hamptons are not cheap, especially in August.