Everyone has chimed in on the what to bring, IMO-here is what I recommend not bringing.
Dont bring the wife, kids or friends that not racers or understand what goes on in the pits. To me they are a distration and all too often get their feeling hurt when you cant give them the attention they need. This for me is a bigger issue on test and tune night. Get comfortable with your car, the track, and the process then bring the family and friends.