Originally Posted by Often1

Rather that focusing on shuttle buses to an airport hotel at DCA, since you've on got one night, why no spend it in downtown DC? Have a nice dinner, see the Mall at night and the like. Outbound to IAD, the bus is just that, a city bus. It's a worthwhile backup if all else fails, but if you are paying for a premium experience in the air, why not do the same on the ground? Cabs and car services are plentiful in DC.

Sunday will beat the traffic, but it won't beat the length of the security line because Sunday PM is a heavy departure time. Access to premium security doesn't help much either because they adjust the # of lanes for premium & steerage to the volume. For a 5:00 PM flight, I would be in my taxi no later than 2:30 PM.