The Musee d'Orsay has the best collection of major French Impressionist and Post-Impressionist painting anywhere in the world. It also has a few other great period pieces. A visit there was a nice and peaceful way to spend an afternoon, exactly what I feel Impressionism was made for.
Above and below: The museum has a great collection of Art Nouveau furniture and decorations, this section was my personal favorite despite the plethora of famous Manets, Monets, Degas, Tolousse-Lautrecs, and other rediculously famous paintings.
These are from a wall display I loved featuring the props from a famous shadow puppet theater from in Paris during the late 19th century. Other figures include soldiers, armies, bourgoise figures, farmers, animals and more.