Every school child should go
This IS the place to go if you're a Civil War buff or you have school children or if you're human because this place will open your eyes to what the word sacrifice means.
I bought a tour book with audio CD at the visitors center for $20.00 and it made for a nice trip. They also have a guided tour in which you drive your car and follow the guide.
Nothing shouts out the horror of war better than Antietam. Such bravery and so many dead. This is one of those places where you feel and hear the brave souls that fell here. The Sunken Road and The Cornfield will have you in tears. Not near as many monuments as Gettysburg so you get a better feeling of how things were.
I took in Harpers Ferry the same day so had to rush at both places. I will do back and the next time I will spend a day at both places.