I came to the Ile Saint-Louis, one of Paris' two islands on the Seine, in search of the original Berthillon, Paris' most famous ice cream shop. The ice cream is sold all over the city now but you have to find the original. It's seriously good, my favorite being chocolat noir (dark chocolate).
But I found Berthillon, and I kept wanting to go back. It's just so lovely and mostly residential, with 17th century apartment buildings, and on a beautiful day, it's pure Paris magic, and like a movie set of what you think Paris should look like. It's close to Notre Dame, so an afternoon spent wandering both islands is time well spent.
You may also spot Angelo Aversa, with his bicycle art gallery, the so-called "smallest art gallery in Paris," of wood cut pieces. They are so nice and, while not cheap (we paid around 100 euros for our small piece), it is on display on my desk and such a great reminder of meeting the artist, and our time in Paris...and of the lovely afternoons spent on the Ile Saint-Louis.