I'm doing the SF marathon this Sunday. It's going to be my fourth time doing this race. The highlight is running across the Golden Gate bridge. The low light is all the time spent in Golden Gate Park, we see about every inch of Golden Gate park. The other low light is that this race has gotten to be too expensive.
I prefer the Oakland marathon that I ran earlier this year. I like the warts and all course through Oakland much better. There's more people cheering at the Oakland marathon and the runners seem a little more laid back and a little more entertaining. Whatever. Just being cranky/Oakland prideful.
Anyway, SF marathon should be pretty fun. Weather is always great, overcast, not too cold and not too hot and not windy, perfect running conditions. The hills are tough though.