One of My Favorite Things To Do In New York
If you have a chance, walk the Brooklyn Bridge. I like taking the subway to the stop right under the bridge on the Brooklyn side (High Street on an A or C train) and walking back, seeing Manhattan and New York harbor stretched out in front of you. You walk on a level above the cars.
If you have a good telephoto lens (which I did not, just a handheld superzoom, so the picture below is grainy) you can get a nice angle on the Statue of Liberty from the Bridge
Other terrific walks that get you out of the concrete canyons for a while are about anywhere in Central Park, but particularly around the Ramble. And on the High Line Park.