DC was a solid trip. Can't recommend it enough. Looks like a great place to drag the kids around. Just be wary that you could wind up with teenagers in the hotel room next door who act completely and utterly retarded.
I was staying in Crystal City which had plenty of options for food and drink and you could spot planes landing/taking off at Ronald Raegan National Airport. Surprisingly, the noise wasn't that big of a deal. Legitimately the most civilised US place I've seen so far.
Anyway, now for my chance to moan about baggage. I'm sick of doing that song and dance about checking in cabin bag bags because 'its a full flight, sir' The amount of overhead space we had flying out of Heathrow was fine. If airlines don't want to run that risk, keep that shit as one cabin bag per customer. Don't give them to option to buy more.