Google "Hotels near 17th and K St in Washington, DC" if you want to see which hotels are within walking distance to the office. However, the downtown DC hotels tend to be very expensive (approximately $250 to $500 per night). The closest is the Hilton Hotel at the corner of 16th and K Streets. Always check on hotels.com or Trivago or similar sites because at certain times of the year (when tourism is down) the downtown hotels are very reasonably priced. I have seen the Hilton near my office for as low as $90 per night.
Another site to find discount rates on flights and quality hotels is hotwire.com .
If the downtown hotels are too costly when you come, the least expensive and most convenient places to stay are in the DC suburb of Rosslyn, Virginia. You can walk to the Metro from your hotel and go 2 stops on either the orange or blue line to get to the office. Go to Priceline.com and look for "hotels near Rosslyn, VA Metro stop". There are always several that are around $100. If you fly into Dulles airport, you can get Metrobus 5-A directly to and from the Rosslyn Metro stop (just $3, takes about 40 minutes).