Wasn't sure if it was a couple days of mtgs and you were trying to get out a couple nights and such...
But another option is Catoctin NP in MD. A long time ago when I lived in the area I had a friend who was a Ranger at Catoctin and he kept asking me to give fly fishing a try and to let him take me to the park. (Like an idiot, I didn't take him up on it). Supposedly they had brook trout there as well as being stocked by the state. It is about 50 miles from DC so if you could slug your way through traffic or beat the 330-700 oclock rush you may get there with a couple hours to fish. Just an Idea.