Having lived there for 30 years, for me, Long Island is about it's marvelous coastlines. The North Shore... from Oyster Bay out to Port Jefferson and beyond, the coast consists of rolling hillsides with many small harbors... just follow route 25A, and turn left from time to time. Planting Fields Arboretum (
http://www.plantingfields.org) in Oyster Bay, is a particularly beautiful photographic location. The South Shore... all of the marshes and reed lands along the Great South Bay, and of course Fire Island. The south shore also has numerous ponds, lakes and streams that ultimately flow into the Great South Bay... follow route 27A, and you will cross over many of these. Lastly don't neglect the many state parks... (
http://www.nysparks.state.ny.us/regions/long_island.asp) most of which were established many decades ago, preserving Long Islands unique environment. These can be fertile locations for landscape work.