When in Paris be sure to go to Place des Vosges. It's a lovely little park or piazza situated within walking distance of the Seine.
It has a perfect square shape and it is lined with sumptuous buildings that are the same on all four sides. In one of the buildings Victor Hugo once lived. At the bottom floor you can find nice restaurants with terraces and even a grocery store with supermarket prices for food and drinks.
On the other corner is a luxury restaurant that I never got into. Looks good, though.
The coolest feature of the Place des Vosges is that people just walk and lay on the grass with nothing holding them back. It's a delight to just lay on the grass and enjoy a moment.
On the adjacent streets you can find lovely little corner boulangeries (french bakeries) where you can buy a nice baguette, pain au chocolat, tarte au citron or jambon sandwich (that you can be shure that it's made fresh in the back).
For the ones that are interested, there is a good knife and razor shop on one of the corners.