Trust me. Go the 1/13 route. It's local roads through Delmarva, but even so, it's a LOT shorter than going around DC. Delaware can be a little stop-and-go in stretches, but otherwise, it's not really that bad.

Don't forget, going around DC, you have DC traffic to deal with.

Every person we have met here on the OBX who is an "OBX Newbie" has taken the "Mapquest way," and gone through DC. The first thing they ask when they see that we are "veterans" is "what's a faster way?"

Plus, you can do a LOT of side lighthousing, if you so wish, though DE (pretty much every light is off 13/1) and VA (Assateague, etc.). Not much through MD, since you're only there for that little square stretch, and everything's on the bay or in other states to cover that coast.

Trust me...it looks better on paper, but after hours in the car, the coastal way looks nice.