After going to the Grand Palais on Nuit Blanche, I knew that I also had to go to the Petit Palais, which is across the street from the Grand Palais in the 8th Arrondissement. We also wanted to go to the Musée Cernuschi, which is an Asian art musée in the 8th. As a bonus, both of these musées are free.
The Petit Palais is definitely a worthwhile musée to visit. The building was built in 1900 for the Universal Exhibition. Today, it houses the City of Paris Museum of Fine Arts. The Petit Palais has an outside courtyard and garden, in which you can drink coffee and have snacks. The first floor of the Petit Palais had interesting pieces and sculptures. There is also a painting by Monet of the Seine.