Originally Posted by
samosa
My choice would be the Residence Inn Arlington Pentagon City. It is a short walk to restaurants and the yellow line as Windhund said. It is also easy enough to grab a cab into the city for 10-18 bucks depending on traffic. It is also next to a FS Renaissance.
The one next to FS Renaissance is the RI Capitol View, these 2 hotels have shuttles to DCA, but not walking distance to metro.
I stayed at Marriott Crystal City and RI Pentagon City, both are close to Metro and Marriott Crystal city has a lift taking you to the metro level (so you don't have to walk outside in the heat).
RI Rosslyn has good location too - walking distance to Georgetown.
I just came back from DC and I rented a car so I stayed at hotels with free parking - once I drove past Rosslyn metro (stayed at HI Rosslyn - free parking) and saw replacement buses and people queuing for them.