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.
The very first place i've been in Paris.
My first month in the city, i spend over 800€ in this bar (true story)
It's simple, warm and friendly, drinks are not so expensive (for Paris...). You can talk with every body, people there are open minded and funny (but only because everybody is drunk)
I love to go to this library and often work there. It is very peaceful and the setting is beautiful. The library is a mine for books about design and architecture.