hey if you havent bought your ticket yet, fly into BWI. I live in Pittsburgh but went to gtown for undergrad and would always fly into BWI. If you fly southwest, the ticket is exponentially less than flying into National (reagan) or Dulles. BWI is about 45 minutes out of DC and you can either take the train into Union Station in DC (about 7 dollars one way, but only runs M-F) or grab a super shuttle which is what I do. The super shuttle time can vary (but its usually an hour-hour and a half bc of other people) and is $35 but takes you to the front door of gtown. This is what I did for my November interview at Gtown and despite the little extra travel time, it is super easy and more importantly much more frugal!
hope that helps 🙂