For the flower freaks among us...
Reeves-Reed Arboretum
http://www.reeves-reedarboretum.org/
It's open the second there's light in the morning, and doesn't close until there's no more light in the evening, meaning you can shoot in any kind of light you want. Flowers are incredibly accessible for shooting.
Leonard Buck Gardens
http://www.somersetcountyparks.org/ and then click on "gardens". Somewhere between Reeves-Reeds flower and landscape intensity, and how a normal arboretum would be. Opens too late for my tastes, though, and closes too early. And sometimes is closed for no apparent reason, which really fries me.
Great Swamp and the areas around the national park there.
http://greatswamp.fws.gov/ They have excellent birding blinds set up, although subject to the schedule of birds that live in the wild - meaning, show up mid day and you'll be very, very alone. Great swampy stuff (duh) and trails. Nearby there's the Raptor Trust
http://www.fieldtrip.com/nj/86471091.htm which has orphaned and injured raptors being nursed back to health and wild release. On the edge of the Great Swamp park is a breeding area for herons. We're talking 10 or so trees that are densely nested. The viewing area is quite far away, they have telescopes for people to use, but if you've got 600-800mm worth of lens, you can get some really nice shots.
And for more info about NJ sites:
http://www.fieldtrip.com/nj/index.html