What days/time of day are you thinking you will ride?
The W&OD is super convenient, and like the others said it is great for running. IMO with the weather this time of year it wont be too crowded to enjoy riding you bike on it either. I would check out Hains Point, its a DC roadie/triathlete staple. The McArthur/Anglers loop out of Georgetown is pretty popular too. Bikenitic does a Tuesday hills ride at 6am if you are so inclined, I am usually not lol. Spokes, Etc. seems to have taken over the Tuesday night ride out of Arlington. Contes in Falls Church has a Saturday ride that rolls at 8am with a similar route as the Tuesday night ride.
Riding/Running the DC mall is a fun novelty that is cool to do once. The Mt Vernon Trail sucks to ride a bike on, unfortunately. I would check out the strava heat map also.
https://www.strava.com/...491/38.87822/hot/all