I drive from Marlborough to Elon, NC a few times a year, so I can give you some perspective. We leave Marlborough on a weekday at 3 am and take I-495 to I-90 to I-84 to the CT-15 connector to I-91 to I-95 and over the GW Bridge to the NJ Turnpike/I-95. We stop at the last rest area in NJ (Clara Barton) which is between exits 3 and 2 for cheap gas and a bio break. We are usually there by about 7:45 am or earlier. We then go right down I-95 through Baltimore and usually only hit short delays near White Marsh Road north of Baltimore and at the I-495 merge just north of DC. We are usually clear of DC by 9:30 am even with delays. So my summary would be about 6.5 hours to clear DC including a 15 minute break at the NJ rest area. I use EZ Pass for tolls, check 1010 WINS radio for NY area traffic alerts on the 1's, and use XM Traffic for Baltimore/DC Metro traffic alerts. The worst traffic we usually hit is south of DC where the roads merge and the traffic to Quantico area all funnels in.