One street you cannot forget to visit in Paris is Rue du Pont Louis-Philippe. There are some great stationery boutiques there including the beautiful 'Melodies Graphiques". The walls are covered with envelopes which instantly makes you want to write a long letter to tyour loved ones! Paper, envelopes, writing materials, stamps, this shop sells it all and every single piece looks beautiful.
The last photo is from Papier +, a more modern stationery boutique but gorgeous as well!
I just wish I would have my own little shop in Paris some day...