Thanks for all the ideas. I have lived about 1 hour from Gettysburg for 8 years and have yet to do much there. Plan on taking my parents when they visit this summer.
I love the idea about the train exhibit. DD9 was just saying about taking Poppy (my dad) to Lancaster to see trains (which DH and I did with her last summer) since he loves them. Now it will be new to everyone!
Your dad would probably love the historic Gettysburg train station where Lincoln arrived before he gave the Gettysburg Address. It's on Carlisle St.