Welcome to Balmer
Nice area you're moving to. My wife and I live in Locust point in the inner harbor near Fort McHenry.
First thing, you don't want a marina in Baltimore. My wife and I lived on our boat in a Baltimore Harbor marina while our townhouse was being build and we didn't like it at all. The water is filthy as in sickening and it takes two hours on the Patapsco river to get out to the bay.
I've had boats on the Chesapeake since 1972 and have been in marina on the Rhode River, Back Creek in Annapolis, the Magothy, West River and finally Herrington Harbour South on Herring Bay (about 25 miles south of Annapolis.
There are lots of marinas on the Patapsco, some reasonably close to the bay. The problem is once you get out you're on the northern end of the bay, still a long way from most of the places you will want to go.
The Magothy is a really nice river. We lived in Severna Park in a waterfront house on Cattail Creek off the Magothy and it took us 45 minutes to get out to the bay. The problem with the Magothy is there are very few marinas and it would be hard to find a place.
Next stop is the Annapolis area and the Severn River. Annapolis is much more centrally located than the Magothy and the Patapsco but it is expensive, one of the pricest places on the bay and it is jammed both with cars and boats. Annapolis is great for restaurants and ambience but it can be a real nightmare getting out of it on Sunday depening where your marina is.
Next we come to the Rhode River/West River. (Im skipping the South River, powerboat heaven) Nice rivers, much less crowded than Annapolis but a lot of shallow areas. There are a number of marinas there, less expensive than Annapolis. Centrally located bu the entrance to the river is guarded by long shoals, Take you over and hour to get out to the bay if your heading south.
Next is Herring Bay. That's where we are now. An hour from Baltimore there are marinas all along Herring bay from Deale to Herrington South most are less pricey than Herrington.
Herrington South is one of the nicest marinas on the bay, very well kept with lots of amenities for when you only do a day sail or you just don't feel like going anywhere. It is in the middle bay area which gives us easy sailing access to Annapolis, the Magothy, the Chester Rriver, St Michaels, Oxford and the Solomons. If we push it we can get down to the Rappahannock before nightfall. When get out of the Marina its another ten minutes to the bay. It costs us $6200 to dock Enchantress, our 46-ft sloop and we feel its worth every penny.
My advice to you is to get a Chesapeake Bay Cruising guide that among other things will give you a list of Marinas, then drive to most likely ones. I suggest this because some places that look very close on the map take a long time to get to because of roads and traffic. To drive to Bodkin Creek from Mount Washington, might take you nearly as much time a my drive to Herrington mainly because the only access is Mountain Road which can get jammed up on weekends. Also you'll get a chance to actually see the marinas and talk to the slipholders.
Good luck and if theres any help we can give let me know