Lynford Morton of PhotoTour Excursions offers two, two, two events in one. (okay, only the older among us will remember that chewing gum commercial. Or was it mints?) Photo lessons and a tour of the area at the same time.
You meet up either at the Lincoln Memorial for DC monuments or in Annapolis (think Chesapeake Bay, U.S. Naval Academy, boats) or in Adams Morgan, a neighborhood in DC full of ethnic restaurants and funky buildings.
Then you get to hang with locals and visitors who show up for the class and talk photography, where you're from and anything else that comes up during your wanderings. So it's fine to go solo.
The best part of the tour was that Lyn gave personal attention to each of us, looking at our photos and showing us how to use various settings.