So you want to take your kids to see Gettysburg?  Here is my advise based on my experience taking my kids:

• Read up on the topic before the trip–kids learn by example (if dad is into it, they will be….): #1. Killer Angels–this will get you pumped to see Gettysburg.  It is a GREAT read. #2. Battle of Gettysburg at Wikipedia–this is a short clear summary.
• Listen on the way–This is the best audiobook on Gettysburg(you can get it at amazon or download it to your ipod at audiobooks in itunes); The kids could only take this 2 hr book on tape in 15 minute intervals, but it is important for you to get through it before the trip to get the kids pumped about the history.
• Gettysburg Museum–FIRST STOP–we went to the Gettysburg Museum first.  It gave the kids a great summary and got them excited to see the battlegrounds (there may be better museums? This one had a hokey pseudo-disneyland re-inactment, but it was good enough.  Remember to get their free brochure of their audio tour (it has a very simple map of the battles–we did not do the audio tour–it was at least 2 hrs long)
• Touring the battlefields–#1. Union Line–Go to the Pennsylvania monument first (you can climb to the top and get a great overview and at the top they have pointers to show you where everything occurred) #2. Go to little round top–this was a KEY defensive position and holding this hill on day #2 of the battle was key to victory–there are some great plaques that teach about some key people–Strong Vincent etc. #3. Devil’s Den–my kids were into the idea of snipers shooting at the Union line from this key rock formation. #4. Confederate line–we ran low on time so we just went to the very high tower at the center of the confederate line–great view of battlefield.
• Patience–my kids must have asked me at least 2 dozen times: “Now who were the Rebels, who were the guys in blue, who were the Confederates, which side was Robert E. Lee on again….” It was all worth it when my son did a speech on Strong Vincent for school….They really do listen.
• Summary of the battles–Day #1. The push–The confederates AGAIN had a significant victory on the first day which made them too confident for the following days.  Day#2. The flank–Lee decided to go with tactics that worked for him in the past despite very poor positioning.  Meade fell back to excellent defensive position, and Lee couldn’t breakthrough at Meade’s flanks.  Day#3. The charge–The most famous part of the battle(s) is one of the most brutal and some would say courageous or crazy ideas.
• Lessons learned–Pride before the fall–age old adage–Lee’s over confidence appears to be his undoing; superior weapons save lives–The Union had rifles that had superior technology to the Confederates which helped them to fire more rapidly; a powerful military is important–although I am not big on guns etc. studying military history has helped me to understand that a high tech/powerful military is important to keep the peace (I recently heard a commentator say that we need to get out of all these other countries that we are in (save A LOT of money), but maintain our military edge…so if there is a problem, we can keep the peace…); location, location, location–the view from little round top was a powerful reminder that the high ground is always key…