It's one of my routes. I hop on the greenway and go north or south, depending on my mood. North is good because it is less crowded from the UWS (usually). The views of the bridge are great the entire way. And then when you get the bridge the lighthouse is really neat. If you keep on going it gets fairly hilly, but you are rewarded with a nice downhill on the way home. I ran into the Bronx this weekend, that was fun. You have to navigate through Inwood park to one of the bridges to leave the island of Manhattan, but it's a fun run.

South is great too. One of my first long runs since moving here was UWS --> battery park --> under Brooklyn Bridge --> up the lower east side --> UN building --> UES and then I cut through the UES and park to get back to the UWS. A 17 mile tour of New York!