Washington truly has an abundance of riches when it comes to cultural performances, particularly when one considers that a fair number of these events are free of charge. The best series of free performances happens at the Kennedy Center -- the Millennium Stage offers a daily dose of arts: classical music, dance, contemporary music, etc, are all performed for free every single day at 6pm. Just keep an eye the schedule online, and make time to either go see the performance in person, or watch online!
When I saw that the Yale Whiffenpoofs - the country's oldest and probably best known American collegiate acapella group - were going to be performing, I immediately invited a couple of friends to join me.
It was a wonderful concert -- quite a few of their numbers gave me goosebumps. Of course, as a Latvian, I can really appreciate good choral performances! The entire performance can be seen online via this link. In particular I enjoyed their version of Simon & Garfunkel's "The Boxer" and James Taylor's "Carolina on My Mind."
If you ever happen to have the chance to see the Whiffenpoofs perform, I highly suggest not passing that up, although the entire group changes over every year, as only seniors can be members.
And if you are ever in DC and tire of the museums, definitely check out what's happening on the Millennium Stage -- and show up at least 15 minutes (if not more!) early if you hope to get a seat!