go skate some hills if you got the time. they're not as steep as SF, but the pavement is so much smoother. it's my favorite thing to do whenever I go back to the city.
you can start at Porte des Lilas and go down all the way to Republique for instance.
(it's Place de la Republique by the way, not Palace
)
Musee d'Orsay is a cool spot too, real close to St Germain. And I used to skate Rue des Saint Peres in that neighborhood too, but it's been skate-stopped to death.
bon voyage cher ami et amuse-toi bien!!