Expo and Start line are easy to access via the Metro. No need to rent a car at all. The Metro will get you were you need to go.

I had heard last year's race was a mess with aide stations and when the first two were undermanned I was concerned. But after the first two, everything was wonderful. Terrific crowd support. Great views. Everything was set up for success. This was one of the better races I have done this year, if not the best. I highly recommend doing this one and making a weekend of it.