My fiancee and I went horseback riding in Gettysburg at Confederate Trails. It was a great experience. You go on a guided tour with several other horses for either an hour or two. We did one hour. The guide will be dressed up as either a Union or Confederate general. You ride at the same speed as the Civil War forces did, just 4 mph. This is one of the things we learned on the tour.
It is a ride designed for people who have never been on a horse before. Neither of us had been on a horse, but it was actually very easy to learn. It was so much fun we actually want to go riding again.
For the price, it was a very good experience and well worth it. It is located just outside the heart of the village of Gettysburg. Make sure to make reservations if you would like to take the trip.