I am too much of a debutante to participate in the Sunday 20 km, 3 hour Roller event, but it sure looks like fun! There is also the Friday night 25 km. event for the real thrill-seeker. They are free and open to the public. Maybe the weather will cooperate and you can join in !
Once every two months they even take on the Champs Elysees.
The day before the tour, get all the details to roll around Paris at www.pari-roller.com.