Don't miss Annapolis
. Lots of boats, chandleries, restaurants, lovely old structures. Bacon and Offshore
Outfitters have tons of used gear
is also lovely, particularly the Inner Harbour, Aquarium, etc.
If you have time, the Eastern Shore offers lots of interesting places, including Kent Island, St. Michaels, Oxford, etc.
You could spend a week or a lifetime exploring the 5K miles of shoreline of the Chesapeake and its tributaries.
Then, there's Philthy-delphia :-) Oh, well. They do have good steak sandwiches, though!