It's a good race. Typical big city event in that it's quite high profile and well organised but with the USMC running it, it has a sort of "non-profit" feel. The crowds are not enormous (compared to NY, Boston, London, or Chicago) -- DC, with its unique cultural mix, is really not a road running city -- and the course is quite compact (in other words, it's 26.2 miles squeezed into a reasonably small area (which makes it good for spectators to see you at a number of different points in the race without having to walk a long way). It's also fast and flat...the sort of place you'd have a shot at a PB. And, of course, if running by monuments is your thing, then you've got an unbeatable marathon for that. I have to say, however, that I'd do New York or Chicago before the Marine Corps, and I'd do Boston far ahead of all three (or any other marathon, for that matter.)