Wife and I and another couple are heading to south central Pa.to see the sites. Gettysburg is our main focus. Plan to set up in that area and do day trips to other places. Help with the other places. Leaving in about 3 weeks and have about a week to spend in the area.
A lot of good suggestions but some are a significant drive in often bad traffic from south-central PA. Some thoughts.
Frank Lloyd Wrights Falling water house near Mill Run PA -
https://www.fallingwater.orgVisit the US Army War College heritage center in Carlisle -
https://ahec.armywarcollege.eduFredrick MD - The Civil War Medicine museum -
http://www.civilwarmed.org