Coffee Express is a nice alternative to Starbucks. I like supporting local places and this is one of the few in downtown DC. As the name of the place suggests, this is coffee on the go. There's no seating indoors, and a couple of tables outside. The coffee is very reasonable, and one of the cheaper places around - but that doesn't mean the quality is bad.
They always have about 10 drip coffee flavors to choose from and also have lots of quality tea options - not your Twinings or stadard Earl Grey. To make things better, they've got a loyalty drink card to entice you to return and eventually get your free cup of coffee.