Your location is great. I was referring to your recommendation to friends when I mentioned being close to the L.
Chicago is a zoo on marathon weekend, but in a good way. It was the first marathon I did and I'm glad. The support along the route is incredible! If the weather is good, there will be people out the whole way, and you get a good flavor of the city.
My husband and I are planning to run it this time too - his first Chicago marathon. Just being in a crowd of 40K is awesome! It really gets you pumped up.
Enjoy the run and the city!