I work in NE Baltimore. I'm not sure if you're going to be staying in Baltimore itself or in the County just outside. Also where are you coming from and how are you getting there?
The only real place to find pipe tobacco in a B&M around Charm City is a regional chain called Davidus. It's... ok. A few tins of C&D/GLP and a couple standards now from Peterson. If you're coming from the south on I81, swing by Winchester, VA to John B. Smith. It's worth the stop.
For food we are indeed known for our crab cakes, but the market price is ridiculous right now. Papa's, Mos, and Kokos are your best bets for an authentic Maryland crab cake. We also have a unique take on BBQ, which we call "pit [meat]". Chaps on Pulaski Highway is the famous one, all the Food Network talking heads stop by there. But the real deal is a tiny little former gas station up to the north a little called Jake's. The food is amazing, worth its... interesting parking. And Federal Hill or Fells Point are where I'd recommend getting your thirst quenched, with tons of small eatery options sprinkled in. And our unofficial drink is National Bohemian beer. But for God's sake, do not order a "National Bohemian"! You want a Boh, or Natty Boh. The pictograms in the bottle caps are fun and get progressively more challenging as the night goes on.
As far as stuff to do, that really depends on what you like. Orioles tickets are still pretty cheap, and it might be fun to check out the ball park that started the current trend of integrating the stadium into the cityscape instead of standing out so much. Ft. McHenry is a great place if you are a history buff. There as much history in this town of mine than I've seen in many places, so if there's a period you like you'll probably be able to find a historic spot to see and appreciate. If you like craft beer, a 30-45 minute trip along I70 to Frederick should definitely be on your itinerary. More craft breweries per square mile than anywhere else I've seen. And if you like live music, Power Plant Live would be your most consistent option.
Annapolis is a wonderful excursion. Parking will be most convenient at the West Street Garage. At the traffic circle, take a right going down the hill toward the harbor (I can't remember for the life of me what that street is called). Poke at the shops on your way down, but the real show is Ego Alley at the harbor. It's always nice looking out at yachts that cost more than my house and car and children's college funds. And while you're there, it's worth the $5 to get into Sandy Point State Park. It's right on the Bay, right next to one of our more distinctive landmarks.
I'm not sure how much time you'll have, where you're coming from, how you're getting there, how often you visit the area, and who you'll be with. But if you've never been, you owe it to yourself to see the nation's capitol. As long as you're not trying to drive down to DC during rush hour, I can't recommend making the trip enough. Park at BWI, take the Marc down, and the metro while you're in DC. There's too much to recommend there, so go through a guidebook and see what tickles your interests.
As far a pipe smoking here, you're ok as long as you're not smoking inside. Outside, Baltimore has too many problems to worry about someone smoking, well, anything.
Since I brought up the problems of Baltimore, I'll touch on them a minute. Yes, the news stories are true. Just pay attention to where you are. Like any other city.
If you want specific recommendations on what to do or see, let us know what you're interested in (beyond the art of turning smoldering tobacco into happiness) and I can be much more helpful. I know Baltimore is not everyone's idea of a garden spot, but still I'm glad you're coming to see Charm City for yourself. Even if it's not your first choice.
Edit: For souvenirs, I'd recommend a can of Old Bay and something with our flag on it. Maryland in general has a simple belief. If you can eat it, put Old Bay on it. If you can't eat it, put the flag on it.
