If you are planning a fall trip to the Gettysburg area, I would suggest timing it with The National Apple Harvest Festival, held the first two weekends of October.
Located just outside of Gettysburg in Biglerville, its a great old fashion country fair. And the country side is beautiful this time of year; the weather cool and the apples great. Lots of great food, vendors of local arts and crafts, pie eating and apple bobbing contests for the kids, music, square dancing, displays of antique cars and old farming equipment, hay rides.
Its a really good time. Ive gone there many times since I discovered it by accident while camping in the area with some friends. And its close enough to Gettysburg that you can tour the battle fields and go to the festival.