rogwilco - Yeah, that's the Frederick Douglas Bridge which connects Anacostia to DC proper. It's part of an offical bike path now, but it's considered multiuse. I rarely see pedestrians on it.

trekker - What does A&S stand for? I try to stay off the sidewalks as much as possible, but sometimes it's just the safer/faster alternative. In some parts of DC, the sidewalks are considered to be part of the official bike paths.

jharte - I'm doing the early midlife crisis career change thing, so my commute is to grad school.

abra - foldings bikes! For a fee you can check them as luggage on most commercial aircraft.