Regarding chipmunk identification, I would like to recognize a friend
and amazing illustrator Nancy Halliday. Nancy illustrated all of the
North American chipmunk species for the Smithsonian Handbook of North
American Mammals. She lives in Chicago, but traveled to areas of the
West to paint these lovely mammals from life (sitting in enclosures with
live-trapped individuals) and study skins. If you search on "chipmunk"
at the following site, you will get a list of species accounts, range
maps, and you will see her amazing illustrations. I can't vouch for the
other illustrators published in this book, but Nancy's multiple pages of
plates of "chippies" (as we called them in the field together last
summer) are the best field guide illustrations of chipmunks I have ever
seen.
http://www.mnh.si.edu/mna/image_menu.cfm