Not doing it but I ran the SF marathon in 2010 and we went out and back on the bridge. Its f*cking cold in the middle during the summer so wear something warm!
Just got a pair of these compression tights delivered
They have pockets over each muscle in the quads/hamstrings/groin etc and come with Ice Packs that you can put in said pockets. I have been Icing the last hour or so and it seems to be a good solution - also, they are built to be run in. If they are comfortable/effective over long distances I will be ecstatic because I will be able to keep Gu/Shot Blox in the pockets for Boston without having to deal with stuff bouncing around.
My legs are destroyed after yesterdays 15 miler w/ workout but I am headed for 10 easy on grass in a few minutes.