This is an event the day before the wedding!!!! We go every year with our families and have a great time. It's worth getting tickets early. There is live music, great wine, and tipsy, middle-aged white women who dance on a hillside, trip, and roll down. All you need is a lawn chair and charcuterie board. If you end up on the hillside, you may be having a midlife crisis, but don't let that prospect deter you. We look forward to seeing you there.
Due to the destruction of marsh habitat (and late summer date), the mosquito population should be at a low ebb. Nice weather permitting, there are monuments and museums to visit. Don't park in DC. Park in Greenbelt and take the metro into DC.
It's a boardwalk. Like Jersey, but fewer Italians. There's ice cream and sailboats and candy. A duck decoy museum if that floats your boat.
The Baltimore Aquarium is always worth a visit. Stay out of the water unless you like cocaine or Hepatitis. In fact, just be aware that even the touristy areas of Baltimore aren't that great anymore. The groom avoided a mugging while walking to his parked car after a work gala. Keep your head on a swivel.
History and Cheesesteaks. Independence Hall, the Liberty Bell, and the Philadelphia Zoo. It's about an hour from Belcamp, so it's closer than DC.
The Naval Academy and the Chesapeake Bay offer plenty of day trip sightseeing, food, and excursions. If you don't mind one bridge toll, it's only an hour away down route 95.