I believe you are in Paris for the first Sunday of the month when many museums are free. Included are Louvre, Cluny, Musee d'Orsay, Pantheon monument, Arc monument (only until 5 or 6 pm though) etc. Maybe you can get the museums out of your system that day. If you do the major ones, I suggest getting there early. When we came out of the Orsay at noon the line was very long.
Also for smaller museums within walking distance of your hotel (suggested walk through Parc Monceau) are Musee Nissim de Camondo and down Haussman not far is Musee Jacquemart-Andre (beautiful restaurant also)-- both enjoyable collections in the collectors' homes with complimentary taped guides that enhance the visit. I loved the Marmottan (husband didn't) but it was a little more difficult to get there.
My favorite grocery is Ed but they are hard to find and you have to do battle with locals. I like their soda called The Best Cola and if you see something interesting grab it, as it may not be there again.