Originally Posted by
MSPeconomist
DCA is great, especially if your destination doesn't require a transfer. However, you can't get to Georgetown easily.
Because of the ease of the metro right at DCA and all the sights to see in DC, this would be one of my favorite layover day trips. However, not sure how many people would ever have an 8-hour layover at DCA...that would be more an IAD thing.
Georgetown is easy enough by cab from anyplace in DC or the airport itself. Also, one great option by metro is to go the other way from the city -- to Old Town Alexandria instead of into DC.