I'll be in Arlington at the end of this week and will be returning home via BWI. Does anyone know a good way to get from Arlington (Westin hotel) to BWI? I've heard that a taxi would be very expensive. Super Shuttle is about $45 (after 10% discount), but the only options for pickup times given by the web site are at least 4 hours prior to my flight. It looks like I could rent a car for about $22 and drop off at the airport, but I'm not sure I want the hassle of driving through the city. Any other suggestions?