Tyson's Corner area (VA) is a popular choice because it's often cheaper than staying inside the "District." The new Silver Line goes out in that direction and there are several hotels to choose from. Plus, it's right off major highways (495 & 66) so you could reach a wider clientele.
Arlington (VA) is also good with lots of hotels near the airport as well as being metro accessible. You'll want to look in the Crystal City area.
DC is difficult just because the hotel rates are so much higher but there are quite a few options in the Dupont Circle area. But conferences are quite common and there are several hotels that do not require hotel keys to access the elevator.
Hope that you have a good trip to our Nation's Capital! There are several threads about dining recommendations and nightlife.