On a recent visit to see family in USA , I visited the Detroit Institute of Arts or DIA . It is well worth a look if you are in the area.

It has a lovely collection, including Paula Modershon-Becker, Max Beckman, Oska Kokoshka and of course the Diego Rivera walls.

http://www.dia.org/object-info/c5404b86-5119-436d-a882-e76b67e4dc1b.aspx