If you're going to the East Coast and want to hike, then the Appalachian Trail is it. You just have to check if some campgrounds are open in March.
Focus on the Delaware Water Gap area which is just off I-80. This site has links to area campgrounds:
Campgrounds - Delaware Water Gap National Recreation Area
Beware the state campground does not open until April 1.
The hike from I-80 up the AT to Sunfish Pond is fantastic. You can also hike Dunnefield Creek and up Mt. Tammity for a great view of the Delaware Valley.
I drive into NYC pretty much weekly for work so let me know what you want to see there. Maybe I'm used to it, but traffic is very manageable.