I have traveled to DC frequently for work - and I'll start with a couple to avoid..
The Hilton - it has had bed bug issues for the last two years, definitely one to avoid!
I have heard the Residence Inn can be a little shady after dark- that area of the city is known for late night street walkers... not out to see the sights...
Not at all a BAD area of the city tough.
Now on to the suggestions!
Hotel Palomar - it is a Kimpton Hotel - Kimpton, known for kitschy boutique hotels, definitely delivers on this one. It is definitely 'upscale quirk' HAHA With synthetic fur runners on the beds, trendy furniture, and upscale lighting and fixtures. It can be pricey, but you get what you pay for! Rates can be had at times for under $200.
The Fairmont is 4-5 blocks from Dupont, and quite stylish.
A few other areas to consider for a trip to the DC area:
Old Town - Alexandria, VA
Mt. Vernon/Convention Center - DC
Silver Spring, MD
Arlington
All nice areas - it all depends on what you are looking for in a trip to DC!