I used to have a friend who did some repo work in Baltimore (that's a whole 'nother story) but when I'd go visit him we'd just walk from one corner bar to the next. It seemed like there was a little local bar on almost every corner and all the people were (drunk) friendly and very chatty. Some places had dart boards, others had pool tables, some just TVs and lots of locals. It was always a blast and we met so many interesting people that you'd never see at the Inner Harbor. Anyway, I have done many of the other things mentioned here and recommend Camden Yards (w/Boogs) and the Aquarium, but I really enjoyed the neighborhood pubs as well. Either way, it's a great city and I hope you enjoy your trip there.