Just went across the 14th St. Bridge atop the East Potomac Park and the Tidal Basin. Big flashing sign says: "
March 21, marathon, expect delays until 1pm". Just to let you know since you're planning to come down to the cherry blossom.
The buds are not yet fully mature and they are not going to blossom this weekend.
Nonetheless, enjoy the outing!
National Marathon - Race Details