Some of us combine several hobbies when we structure our major vacations around Worldcon. Doing this, I have flown a light plane (Cessna 172 or Piper PA28-180) to several Minicons and ConAdian (1994 Worldcon in Winnipeg). With the help of Karl Ginter, I have gathered information for others who might be planning to fly a "General Aviation" to Bucconeer.
There are a couple airports you might consider. Most obvious is Baltimore-Washington International Airport. BWI has a contingent of small planes along with all the real jets. There is train and light rail service to Baltimore. It's about 8 miles south of the Baltimore city line and has the usual transportation into downtown Baltimore. Probably the easiest airport to deal with on the ground.
Second is Martin State, which is about eight miles north of town. Martin State has a tower and is fairly lightly traveled. It is shared with several Baltimore groups of the Air National Guard, which makes for some interesting traffic (cargo and A-10's) some of the time. Easy to fly intoKarl did a bunch of his flight instruction therethey're friendly to small planes.
Third is Westminster, which is about 8 miles west of town. Don't know much about it except that it has landing lights. Further away to the southeast, but better known to us, is Freeway Airport. It's a small strip that sits out on Route 50, just outside of Bowie, Maryland (which makes it kinda far from Baltimore).
It's the smallest of the airports but the people there are pretty nice. Karl did most of his flight instruction there and can say they were okay back then.
Don't bother with College Park or Suburban Airport. College Park is really far away (D.C. suburbs, on train to Baltimore and D.C. subway), has really big trees at one end, and an above-ground subway station at the other. Suburban has the big tree problem and is right on the edge of the BWI ARSA.
I recommend BWI and Martin State. I have found that large airports at smaller cities, such as Indianapolis or Milwaukee, are no problem to fly into for anyone who is comfortable with control towers or "reliever" airports such as Palwaukee or DuPage in the Chicago area.
The Class B and C airspace means you have to have a transponder with Mode C, with which most planes today are equipped. You need to call "Approach" before entering that airspace. I recommend calling at least 15 miles from the edge of the Class B/C airspace.
If you are totally averse to flying into a Class C airspace, I agree with Karl's choice of Freeway Airport.
Be sure to obtain the correct charts, especially the Sectional and TAC (Class B) for the Baltimore area, even if you are IFR. Because of the proximity to Washington, D.C., there is a lot of "Special Use" airspace such as various locations used by the President of the United States.