I am located almost exactly half-way between Washington D.C. and Baltimore, according to the AACW map right about where the Patuxent river crosses the rail-line between the two cities. That puts me about 90 minutes from Gettysburg.
I go to Gettysburg every November for a miniature figures wargame convention, held there in the Eisenhower Center. In fact there are three such major conventions held each year in the Pennsylvania area:
Cold Wars - in Lancaster (usually March - just had it this weekend Fri-Sun)
Historicon - in Lancaster (usually July - this is the largest one in the country with many people and attractions - runs Thu-Sun)
Fall In - Gettysburg (usually November - somewhat smaller but always interesting - runs Fri-Sun)
There are also many other similar conventions in other parts of the country, but those three are the largest and organized by the local chapter of the HMGS (Historical Miniature Gaming Society). You can see a listing of all the upcoming conventions at there website:
http://www.hmgs.org
I would highly recommend attending one of these conventions if you get the chance, even if you don't care much for miniature figures. For those interested in military related history, art, movies, music and games in general, it verges on Nirvana.
I also belong to a figure wargame group in my local area that gets together every Thursday for battles. Currently, we are doing a 15mm game of the Battle of Chickamauga that has been going on for about five weeks. I have command of a couple divisions in the Union center and right now I'm trying to hold on against a coordinated Confederate push. I am getting my tushy handed to me!!