It'd been quite a few years since I stayed at The River Inn in the Foggy Bottom part of DC - but now it's a European-style all-suite "luxury boutique hotel" and for that reason, along with the comparable price and the quiet townhouse-filled neighborhood, I'd consider it a competitive choice to better-known luxury brands.
That said, downtown DC traffic is horribly congested and slow, and now that DC taxis are on meters, rather than zones, it's prudent to be close to where you will be doing business. I spent $20 trapped in a cab in a gridlocked Washington Circle recently, just watching the meter ticking while we didn't move one inch, and if I hadn't had my baggage with me, I would have jumped out and walked in a third the time and half the cab fare to the hotel!
To me, The River Inn works perfectly for my type of DC for several reasons. It's southwest of Washington Circle, near George Washington University, the State Department, the Watergate Hotel and the Kennedy Center. All are walk-able in 10-15 minutes, so is Georgetown west across the Pennsylvania Avenue Bridge. The Metro is accessible in 5 minutes at Washington Circle. If you're in town for tourism, the Washington Mall and monuments around the Tidal Basin are a short cab ride away, or an easy 20-30 minutes by foot. Even the Potomac River bike/hike paths and boat landings are relatively close.
DISH restaurant is said to be quite good, and its bar is convivial without being too noisy for a solo Womantraveler. You can tell that the crowd is hip, stylish and probably high-tech.
If you have the option, ask for rooms ending on 11 or 12 in the back corners on any floor (preferably higher up), as they have a solid wall of windows facing south and west - in my case, toward the Watergate Hotel. That scene was a happy memory because back in college, living in a nearby brownstone for the summer, we shopped in the Watergate Safeway before the Watergate Burglars made it notorious.