look for places in the Dupont Circle, Foggy Bottom, Capitol Hill & downtown areas or the Crystal City & Pentagon City areas of Arlington.  The Metro is not overly costly and in those areas there are plenty of restaurants you can walk to.  If you go to the Tysons Corner, Dulles/Herndon or BWI areas, they are pretty much automobile only areas (at least until the Metro extension to Tysons opens next year).  Plus if you're in the DC or Arlington areas mentioned, you're also easily accessible to a large client base, the Convention Center, most of the larger lobbying & law firms, and most of the hotels frequented by travelling businessmen.  
Perhaps some other providers who visit frequently can PM you some hotels they've had good experiences with.

...between Metro, Uber, taxis, the Circulator, and two feet, I get from Point A to Point B, just fine.

   Welcome to DC and have fun!

Hugs and Kisses,
Kelly

I travel here often, and usually don't get a car. Between metro, cabs, and the hotel van, you don't need a car at all. Plus, if you stay in a central location (such as vamikey suggests), you don't want to pay for parking, and it is easier for the clients to visit you.
You can get to all the sightseeing spots without a car. I usually stay in NOVA, primarily due to business, but anything along the metro has good hotels, lots of restaurants, and many have good shopping - be sure to check out the Fashion Center at Pentagon City - connected to the Pentagon City Metro stop.
DC is a GREAT city to visit. They have something to satisfy almost anyone's desires. I am sure you will have a great time, both personally and professionally.

if you are comfortable bicycling on city streets.  With so many bike lanes here, DC is a great city for cycling!

If you live near a metro, really see no need to own a car - major pain.  The new areas like "H" street, and established areas like Crystal City in Arlington, VA make it unnecessary to own a car.  If you're young, groceries are in walking distance and most things are metro accessible.  Only if you wanted to do a day trip to somewhere would you need a car, then I would highly recommend renting or doing Zip car if you really felt you needed one.  Having to go to DC Dept. of Motor Vehicles (DMV) would be reason alone not to get a car and license in DC.  Throw on sales tax, property tax (yearly), insurance, fuel, depreciation on car, maintenance because of crappy roads, break-in to car (happens regularly, especially if you're dumb enough to leave a purse on your seat or iPod/iphone, etc.

If you have friends with cars, even better - they can drive

..... some suburbs in NoVa (outside of Arlington, Falls Church, Alexandria, Springfield) I wouldn't recommend NOT having one. I personally couldn't imagine living in Tysons Corner or further out near Dulles or like down out in Woodbridge or something without one.

Thank u all!!!

Thank u thank u!! I have gotten great responses both via this post & PMs... I'm starting/planning my trip to DC for mid sept & excited... I'm so glad to find that DC is public trans friendly.... Everyone has been so helpful.. Thank u thank u...  

Can't wait to provide & be a tourist in your historic city....  

Maybe ill have lunch with the president...  Lol....wink wink....  

Thank you again
Gemma