I hear ya on the striper run. Like Rob said, occasionally nicer fish will mix in with the schoolies (I've caught several keeper sized stripers this summer), but it's mostly smaller fish. Some places that will hold larger stripers are the Tidal Basin, Gravelly Point, Chain Bridge, and Four Mile Run. My personal best this summer was a 22-inch fish in the Tidal Basin back in early June. A really good fish for this area is around 30-inches.
I caught a fair amount of stripers in and throughout May and June but haven't really seen any since July. However, I imagine they'll start moving back in when the water temps start falling back into the 70s and below in mid-September/October. Most fish migrate in and out of the area, but there is a healthy population of residential fish that make the river their home.
I'd like to get out on the Potomac and fish closer to the mouth of the Chesapeake in the hopes of hooking into some nicer stripers, blue fish, and maybe even a redfish. If anyone has any information on this or would want to take an exploratory trip out there, let me know!