I am always moved by the NYC Marathon and generally make a point of watching it in Park Slope.
Here’s a nice marathon map from the Brooklyn Paper. Brooklynites can see the runners run on Fourth Avenue starting in Bay Ridge.
I always think Third Street and Fourth is a great spot to watch (the lead runners will get there around 9:40 and the rest around 10:10).
It’s about 6 miles into the race and the runners still have a lot of energy and joie de vivre.
But the runners also run through Forth Greene, Williamsburg and Greenpoint.