If you live in the Washington area, you really have to go to the Kennedy Center (for the performing arts).
Every day at 6 p.m. there is a free show and this program is called “Millenium Stage” (on a first come first serve basis).
There are several shows every day at the Kennedy Center. It is a huge building that you can see from the Potomac river. There is also a very large statue of JFK in the building.
We were there a few weeks ago with my son. We saw the performance of two Israeli artists: Yinon Muallem (he lives in Istanbul, Turkey) and Guy Mintus (a 22-year-old pianist who lives in New York City), and we had a blast.
You can go to the Kennedy Center with their red shuttle at Foggy Bottom metro station. Again, it is free.
All the free shows are also online (but again live music is a much better experience):