Hi Daniel,
Smallmouth fishing is great out of a canoe around riverbend park and up (caveated for general smallmouth population issues - their populations are in a down cycle right now). You can access the main stem potomac from multiple boat launches along the C&O Canal. Seneca Breaks is wadeable and probably my favorite local smallmouth bass spot.
Know before you go - Gravelly is the ultimate hot 'n cold spot, in my experience. I've fished it at least a half dozen times and only had success one time (it was a lot of success that time - proof attached). It's a well known spot and it gets some pressure. This would be the time of year to go, though, I should think. I would suggest low light and a perfect outgoing tide as critical factors in your success. Parking is probably an issue now. They close the gravelly parking lot until like 6 am (idk look it up) and you used to be able to park across the parkway (and then run across in wading gear) but I think that parking lot might be reserved for airport activities now.
That canoe can get you to some good striper fishing around the mouth of the Patuxent (Solomon's Island) just right in the harbor there. Puppy drum may also be present. Another good place to try to shore fish for striped bass is Kent Narrows on the other side of the bay bridge.
There's a good run of Puppy Drum in the bay this year, but the best place to go is Crisfield, MD, which is a solid 3 hour drive from DC. Once you get yourself out there though it's an amazing spot to fly fish - trout, bass, puppy drum, flounder.... it's my favorite shallow water spot on the bay.
Good luck! Hopefully we can resume beer ties someday soon and can chat about your experiences at these and other spots!
Misha