The majority of creative agencies in Paris are located along Canal Saint Martin so everyday the banks of the canal are full of artists and creative people enjoying their lunch break. If one is lucky enough to be around the canal on a sunny day its the best place to enjoy a drink.
It's always good to check out what's happening in Fondation Cartier. They have lots of really good exhibitions of modern art, and the gallery itself is very beautiful. Perfect for seeing works you already know as well as discovering new artists and inspirations.