I know exactly how you feel! When I moved clear across the country and left dearest Shop Girl behind I wondered if I was destined to spend the rest of my life returning poorly chosen fashion items to various department stores. However, it's not the end of the world, help is at hand.
While I am not familiar with the Washington DC area, I am very familiar with the Bloomingdale's Personal Shopper service, which I have used on more than one occasion. This is a great way to get a basic style education. I would suggest that when you make your initial appointment you ask to work with someone who has been doing this for a few years. Be very specific about the looks that appeal to you and the image you are trying to create. Also, specify that you are trying to create a timeless and classic basic wardrobe, with a few updated trendy looks to balance it out.
Also, one of my favorite past-times is watching "What Not to Wear". Clinton and Stacy are great at nailing the right look for the right profession at the right price, and making it all work with your particular body type.