We went to the reenactment two years ago, and it was truly incredible.  Also did some of the tours available. - walking the line of Picketts Charge was awesome.  There are also scads of vendors there - anyone going with children should bring plenty of money or great ability to say "no!"  They not only include the usual guns and hats, but such esoterica as original dress patterns from the period.  We spoke with one woman whose son is an avid reinactor and who took part in the most recent "big" (as in some 5- or 10 year increment) reinactment.  She said there were more reenactors there than there were soldiers in the original battle. She also said it was pretty funny to watch them all (in character) charging the stone wall and then stopping to haul out their cameras to take pictures of each other.
You might also want to check into the Massachusetts reenactments, I know they do the Battle of Lexington and Concord for the Revolutionary War fans - that was fun, because the "dead" guys are all lying on the ground laughing at their friends.  There also used to be a Civil War one in Carver, MA., charging calvery against a gun emplacement, also campsite complete with medical staff and camp followers (ahem).  I also think there's a huge cotillion at the end of the season, I think at Lake George in NY? Anyway, have fun, summer's finally getting started here in VA, 84 degrees yesterday.