Conte's is in Arlington, not far from the Ballston metro (they're at Wilson Blvd and Quincy St). I've only been there once so I don't know much about them. I do know a guy who likes their shop.

There's also Revolution Cycles in Clarendon so that's also metro accessible.

City Bikes in DC also has a good rep.

I actually live a couple miles from Spokes in Alexandria but when I was bike shopping I liked the folks at the Bike Lane better, so for me they were worth the drive. Not to say that anything is wrong with Spokes - they're a great shop - but to me the service at the Bike Lane is more personal and they really do a great job with bike fitting. I don't find Burke to be a problem to get to and there's a Walmart and Kohl's nearby so it's easy to combine errands when I'm heading that way. I don't actually find myself in Reston that often but when I am there it's because I'm riding my bike, so I'm thrilled that they now have a store right next to the WOD. On Saturday I did a ride that started in Leesburg and since I needed to have my rear wheel trued, it was super convenient to stop in Reston and have them take care of it for me.

I've never been to Proteus because yes College Park is too far to drive most of the time. I don't drive to Dupont to go to bars and restaurants, either. But I have heard lots of good things about Proteus.