I have visited in 2010 both Monet´s house and nearby (short walk) Musée des Impressionismes the same day and found the latter certainly worth a visit. You will see there paintings of lesser known artists, but some I liked as much as those painted by the more famous artists. The museum explains and shows in how the works are displayed the history behind Impressionisme (influence of photography for instance) in an easy to oversee collection and gives really more insight about this Art Movement. More insight means more feel and to my opinion this museum does, not a waste of time if you ask me.
Really have to dig in my memory, so unless I missed something can't remember works of American artists during my visit, but in the meanwhile there can be changes in the exhibition ofcourse.