If you're into fine timepieces (fancy watches), there are tons of stores on either sides of the bridge along Rue de Mont Blanc. I spent 1/2 day oogling over $100K watches.

Walk around the Old Town, where you can see parts of the old city wall, and cute little shops. Wear comfortable shoes, cause it's hilly and cobblestone roads.

Check out the lake and the giant fountain (is it still running full blast in the winter?)

Enjoy