The Orioles play at Camden Yards in Baltimore. It is a great stadium and the drive takes a bit over an hour from DC. The Inner Harbor at Baltimore is only 6 blocks from Camden Yards and is a fun place to spend the afternoon and then go to the ball game. The Orioles are not doing good right now but it still would be fun to see the game.
The Washington Nationals have a brand new stadium in Washington DC. The team is not doing good at all but still the game would be fun to see.