[quote="DC Runner"]I think your best option is the treadmill - it's the closest you're going to get to the actual thing without running hills. Cycling is a non-impact activity and generally doesn't translate well to running. You could run highway exit/on ramps as a not-so-fun alternative.
While San Francisco is a very hilly city, its marathon is surprisingly not so bad. The course doesn't run through the middle of the city, so you're running around the worst hills. Best of luck!
Thanks! I've found a few TINY hills. I'm going to try and work those in as much as I can, aside from the treadmill once a week. But I'm glad to hear that the SF marathon course isn't as cruel as it could be!