Welcome to the area, the best ones in the metro area are in maryland, Scales TFW in cloverly is the best IMO, Then Congressional in rockville, and Tropical fish world in gaithersburg. In VA near you the best would be the virginia pet center(their sign says superpets not virginia pet center FYI) in annandale. Which is where I shop as I live in Burke. Heading into alexandria is wally's which has been around for a while, but i never really liked them, and there is a new store just opened up in alexandria called Pristine Aquariums which is like 3 or 4 weeks old. hope that helps
For VA, I only go to SuperPets now. At Wally's, which is seriously 5 mins from SuperPets going east on 236, you can get better deals on a few pieces of equipment and they are going through a pretty big renovation so I'm sure in another month or two they'll have a better fish selection. SuperPets has some plants but not many and are usually in poor conditions unless you learn their receiving schedule and get there the day of. They also have a hand full of mother plants in much better condition.