We had the privilege several years while we lived in Paris of seeing the French Open Tennis Tournament at Roland Garros. Among the many current stars we bumped into in the back practice courts were James Blake and Andy Roddick, when both were relatively unknown. We also spent several hours watching Justine Henin (now Henin-Hardenne) working out with here coaches. Justine was very gracious and came over to chat with us after her practice session and give us her autograph. We also bumped into a young shy player who was standing with his coach off to the side relatively unattended -- it turned out to be Roger Federer, though we didn't know it at the time. I had my autograph book with me but decided not to get his autograph because he didn't look like a very important player!
Our favorite day of the tournament was the day before it opened, which was a day when many of the players played 1 set matches "for fun" and the ticket proceeds benefited a local charity. For the incredibly low price of 15 euros, we had access to all the events and managed to get front row seats to see Michael Chang, Anna Kournikova, and Fabrice Santoro, play in their various exhibition matches.
All in all, the Fench Open is an exciting venue -- you can rub shoulders with the best names in tennis, the atmosphere is fun and lively and the players are very accessible.