Lots of choices popping up. In terms of height, you're looking at some of the new places near Tysons, or Reston or Arlington.

Tysons downside is that its still sort of a ghost town at night. Its going to take some time for it to really develop.

Reston works well (Reston Town Center area) but may skew a bit older and can vary from pretentious to "urban" depending on the time of day. Lots of new $$$ showing off in Reston.

Clarendon is a great choice for someone under 30. Rents are quite high though. Clarendon can be as pretentious or as "dive-ish" as you want to be. I used to live at Whitlows for several years and its never changed. Everything around it has changed....

My final thought although which is close for those who drive would be the Mosaic District in Merrifield. Very fast growing. I don't know much about the rental market there.