Hi there,
There are plenty of great ways to explore Maryland but I would say that having your own car rental is the way to go as you can set your own pace and gives you the freedom to do what you want and see what you want.
Annapolis and Baltimore are must see places during your Maryland Tour as they offer plenty of historic sites to see. In Baltimore Fort McHenry is high on the list of historic tours in Maryland to explore.
Other sites pertaining to more recent history in Baltimore include the
Edgar Allan Poe House and the Babe Ruth Museum.
In Annapolis Maryland tours should include the Waterfront Warehouse, an old tobacco storehouse that also features a three-dimensional illustrative model of the harbor in Annapolis.
Hope this helps
Vacationbuddy