The most common Gettysburg battlefield tours are on the road traveling by car, motorcycle, or bicycle. You can wander around as you please (as I usually do when looking for a picnic spot!) or you can take one of the Gettysburg tours to really understand more about the significance of the places you're seeing.
Civil War Tours
There are several Civil War Trails that travel through Virgina, West Virginia, Maryland, and Pennsylvania if you want to take a longer ride as part of your Gettysburg vacation. Take a look at this Civil War Discovery Trail book for example.
The Auto Road
These signs are posted around the Gettysburg battlefields and through town to mark the Auto Road Tour. I did it once with my family, and we really enjoyed it. You rent the tape or CD from the tourist center or borrow it for free from your library (out-of-state visitors cannot borrow from the library in Gettysburg) to listen to as you drive around. The signs are there for reassurance that you're on the right path, but even when not listening to the tour, I know that I can follow the signs to guide me through the maze of roads when I'm looking for a certain site. The really nice thing about this tour is that you can pause it if you get stuck in traffic or if you want to get out and explore the Gettysburg memorials.
If you want to drive yourself and have a more intimate setting than Gettysburg battlefield tours by bus, you can pick up a Gettysburg National Military Park Licensed Guide to ride with you for a fee. All you need is an extra seat. My mom remembers that when she was little, vehicles pulled in to pick up a guide at the little stone buildings along each road leading into town. The buildings are still there, but now serve as restrooms during the summer months. You now pick up tour guides at the park visitor center.
There are some U.S. Licensed Battlefield Guides willing to do motorcycle tours! Tours with a guide last about 2 hours, but you can arrange longer, more detailed Gettysburg battlefield tours if you want. Obviously, on a motorcycle tour you will make stops at important sites so the guide can talk and explain things. For motorcycle tours, contact Phil Cole 717-642-5444 or Jim Roubal 717-337-0528.