I went to the New York Giants training camp a few years back (when I liked american football more). I can say training camps are a cool experience. Most of the players are very accessible and in a good mood. If the player is less popular, but still one of your favorites you can sometimes even have a short conversation with them. And of course you get to watch them practice. It's a pretty good deal. Not for everyone though...only those really into the sport of american football.