If you can get out there now - any of the beaches will be void of people (perhaps except for the occasional "lonely walkers" - who are studies themselves).
I'd particularly recommend going to either Sunken Meadow, Wildwood or Hither Hills State Parks.
Also, it's "greening up" time at the North Fork wineries. You'll need to ask for permission I presume - but if you get it - you'll likely find some nice shots of the vineyard rows on undulating hillsides just showing early growth.
Closer in - you might try West End Beach at Jones Beach - or the marshlands b/w there and Long Beach. The latter may involve some hiking - or better yet - if you can get your hands on a boat....
Good luck.