The Chesapeake has lots to offer. Sail in whatever direction the wind gives you the best sailing.
That said, you hit on the things I would mention first. You will have a great time at the GAM and the show. Pay a visit to St. Michaels. You might want to do the trip up the Potomac to DC, simply because there are plans to "develop" the waterfront that will eat up most of the anchorage space. So going, going, gone... At the least, the lower Potomac is worth exploring. Wide, lots of small rivers and inlets. Check out St Mary's. Just up from the Potomac on the way north is Solomons Island in the Patuxent River. Some good deep water exploring upriver there, too.
Go in any direction. There will be something interesting there.
