I live in Rosslyn and it really is dead at night. That being said, Georgetown is a short walk across Key Bridge. But like Dupont [and Courthouse/Clarendon/Ballston] the primary descriptor is "party type." Northern VA near DC along Wilson Blvd - Clarendon - is one bar/pub after the other all surrounding the metro stops. (There isn't as much between metro stops)

While there is some real good food (the Iranian joint near the Clarendon Ballroom is great), it's not really - IMHO - a place kids would like.