If you like Paris and like to sew, go buy the July 2013, Number 167 edition of Threads magazine (on newstands now).
There is a great article by Susan Khalje about sewing related stores in Paris.
Susan Khalje is a well-known couturier/writer/teacher who also conducts sewing tours of Paris. This article is key reference material for any Paris-phile and/or sewing enthusiast. Also, go online for a companion piece on finding some of the difficult to locate places she mentions.