I'll be traveling in New York City during the marathon. How should I plan around that event? I assume that getting to and around the neighborhoods that the course passes through will be challenging by any means except subway. Should I plan to avoid those areas entirely, or does the city mostly continue to function as normal on that day? If I need to be at a specific place at a fixed time, should I keep fairly close by, to ensure that I can get back in time?
I am not really interested in watching the marathon, and I'd prefer to keep my distance from massive crowds. If it's possible to get around and to the usual points of interest (or whatever latest, hippest, off-path spots) without too much trouble, I'd like to do that.
(I think the question can apply somewhat broadly as I've asked it, but I realize some may disagree. In my particular case, I have half a day to spend before I depart from LGA. The course map for 2013 is linked from here, for reference.)