We went to check out the mountain laurel in our favorite spot on Saturday and it's coming on strong -- if this rain doesn't knock off a lot of flowers (and I think it's been gentle enough that it shouldn't) they should be just beautiful this weekend.
I'll tell you ours: the Rachel Carson Trail along the Northwest Branch of the Anacostia. Park at Burnt Mills Dam (or take one of the Z buses from Silver Spring to the Burnt Mills Shopping Center, whose anchor is a Trader Joe's) and head upstream -- from the dam it's less than half a mile to a hillside that is covered in blooming mountain laurels right now.
Click on the map for driving directions, or check WMATA for the schedules of the Z buses and some RideOn buses that also go by this spot (you're aiming for 10765 Colesville Road).
View Burnt Mills Dam in a larger map
This may be a ways out if you're coming from points further south -- so tell us, what's your favorite spot for mountain laurel?