I mostly use back streets through Olde Town Gaithersburg (with a few creative shortcuts). I use a mountain bike with "cross" tires to help out with shortcuts. I ride almost every day, except if there is a "real" good chance of rain or the roads are icy. During the summer months, I typically extend my commute to around 20 miles each day.
I used to commute 35 miles each way by car. After 10 years I finally got fed up with the traffic, changed to a job closer to home, and been biking ever since.
My web site is BikeWashington.org