For some shorter pieces, I'd recommend taking a look at _The Writer's
Presence_, eds Donald Atwan and Robert McQuade.  I do use this book for my
Freshman Comp classes, but there's a wide variety of shorter creative
nonfiction pieces therein--Terry Tempest Williams, Alice Walker, Langston
Hughes, Louise Erdich, Hurston, Carver, Judith Ortiz Cofer, Didion,
Frederick Douglass, Henry Louis Gates, Jr., Donald Hall, George Orwell, EB
White, Adrienne Rich, Leslie Marmon Silko, Annie Dillard, Maxine HOng
Kingston, Walker Percy, JAmes Baldwin, and even TWAIN's "The Damned Human
RAce"....also, many more I can't recall.  2nd edition, UCBerkeley.
Various examples of the range of possibilities for crea.
nonfict.--expository, personal or arguementative (Twain's piece is listed
under the "expository: contending with issues" section).  Many of the
pieces are excerpted from longer works--there isn't, sadly, time to read
everything!