In case you (or others) don't know, the movie Gettysburg is based on The Killer Angels, with the same focus on Lee and Chamberlain. It's very long, but good -- much was filmed on site, and Pickett's Charge is done in real-time. Harrowing stuff.
Also, let me plug the battlefield itself -- I just visited a couple of weekends ago for the first time as an adult. If you've read about it or seen the movie, it's a fantastic place to see. Unlike some Civil War battlefields, standing there really makes it clear -- you can look down from the top of Little Round Top, and you can look across the field of Pickett's Charge from both directions.