I'm flying in to DC from Boston this coming weekend to attend a conference. I'll be staying near the Washington Convention Center and I'm looking for some good restaurants within walking distance (or an easy cab ride). I'm looking mostly for places on the cheaper, more casual side but would maybe splurge one night on something more expensive (entrees low 20s). I'd be interested in cuisine unique to DC, something that I couldn't find in Boston. Thanks in advance!