When I subway in, I do every thing I can to avoid transfer stations. I'll walk to Capitol South to avoid L'Enfant.
The closest red line station, yikes. Probably Union Station? Seems like a long walk. We've taken the Circulator bus there before and after a game, but that's worse than walking to Cap South and transferring at Metro Center.
Might try walkng it some day when the weather's nice and it's not dark.
Edit: 35 minutes according to Google Maps. Cap South is 18, so it's about the same distance again.
