Potomac Pedalers has a variety of rides and lots of riders. You might want to go on some of their rides. Most are on the weekends. Same for Oxon Hill bike club, which has alot of rides in Maryland. Babes on Bikes is an organization in the area mostly of stay-at-homes, but they do ride during the week.

There's also a triathlon club that is pretty active, but I don't know anything about them. Worth a google.

Other than that, DC is a great place to commute by bike, and that is the best way to get cycling in during the week if you work away from home.