She attends one of the Colonial YSA wards and has had a great experience, even enjoys the institute classes. That might be what you're referring to when you mention Crystal City, but I think "little Provo" is actually in Arlington. She commutes into the District though, so I can't address the commute to Tyson's Corner. She can't wait to be done with the Metro.

I think there is a very active internet presence for YSA kids in that area, I think it would be pretty easy for you to get your questions answered. If I recall, there's an LDS listserve for places to stay, no idea how to access it or what that even means.