I have read all the suggestions and most of them are pretty good, but your last question is where do you train? Well if you live in the city.... DC you will have to deal with all of that, but DC has a bunch of little cities all around it with their own downtown areas.

Another good location is Alexandria VA, but since I grew up outside of Annapolis area I am biased towards those areas. I live in Chesapeake Beach, MD and commute into DC area every day. Sadly though, not by bike.

I decided to move to the eastern side of DC to get away from all the congestion and type A personalities of DC and western suburbs. I work just outside of the DC line in Maryland but live on the Chesapeake Bay in Calvert County. Its only 30 minutes by car to a metro station and bus routes are available as well. The countryside in Calvert County and Anne Arundel near the Chesapeake Bay is second to none for riding in my opinion and I have lived in most parts of the state except Western Maryland. There are a couple great clubs in the area that offer great club rides in both Calvert County and Anne Arundel County closer to Annapolis. The roads here are long and hilly with great woodsy areas and nice views of farmland and the bay in some places.

Here is an example of a relaxing weeknight ride... you can add the speed and heart rate. I do it slow and easy.
http://connect.garmin.com/activity/9359091