I never come home from Gettysburg empty handed. In addition to a few books I also picked 5 of the Gettysburg battlewalks DvDs Produced by the Pennsylvania Cable Network (PCN). These battlefield tours are conducted by Park Service historian/park rangers or licensed battlefield guide. I chose the DvDs that had tours conducted by historians/guides I was was familiar with. The programs run anywhere from one to two and a half hours. There are about 12 walks available for sale in Gettysburg that run in price from $15.99 to $25. The PCN website sells them for $25 and lists 89 different walks! Here is a link to PCN which also has a list of available Gettysburg book lectures.
The Herbst Woods tour pictured is conducted by Park Service Historian Scott Hartwig. This program is 2 hours and 25 minutes long and is an in depth coverage of the fighting that took place on that part of the field. Harwig is not only knowledgeable about the subject but also weaves a human element into his presentation.