Throughout the semester I am going to refer to a set of maps made by the Census Bureau (with the help of Cindy Brewer at Penn State) based on 2000 census data. It is a well constructed composition of maps that display a wide range of thematic data using several different symbologies.
Here is the link: http://www.census.gov/population/www/cen2000/atlas/index.html
The pages take a bit to load (as pdfs) but the quality is excellent. You can use them as a reliable source. Look at them closely. How do they deal with noncontiguous entities? How do they classify the data? Look at layout, figure/ground, legend design, basemap, etc.