I grew up in Annandale and have ridden the W&OD many times, it's a nice trail with a lot of regional access. I also worked in Rosslyn several years ago and regret not having commuted by bike, it would have been ideal. I now live in Alexandria and ride about 7 miles into Northwest DC each way every day. The Northern Virginia area has become horribly congested with traffic extending peoples' commutes to, often, intolerable levels-as riders we're immune to congestion, delays, road closures, etc. Welcome to the area and to Bike Forums, congrats on choosing to ride-you won't regret it.