I used to live in the area. Now I visit a few times a year. For my purposes I narrow it down to two choices:

1) Stay downtown, in an interesting neighborhood, near a Metro stop. Pay more in exchange for being able to walk to some things and take the Metro to others.

2) Stay across the river in Virginia near a Metro stop (e.g., Crystal City or Rosslyn). Save a lot of money in exchange for the commute taking slightly longer.

Note, I do not consider staying near a far-away Metro station or off the MetroRail grid unless my purpose is more to do/see things near that site that to visit downtown.