My husband, granddaughter and I stayed at the Embassy Suites that is practically next door to the Americana. It was an easy walk (about half a mile) to the Pentagon City Metro Station. The neighborhood felt very safe to me and the station is in front of a shopping mall with a great food court. Our hotel had a shuttle that ran to and from the metro station so check for one at your hotel.
PS my granddaughter said riding the metro reminded her of Space Mountain because of the dark tunnels!