Michigan's Observer & Eccentric newspaper group ran a nice little Introduction to Graphic Novels piece in their "Hometown" section recently:
Graphic novels: Great reading for all ages
Graphic novels appeal to comic book fans and novel readers alike. To some, the terms “graphic novel” and “comic book” can mean the same thing, but comics are normally much shorter than graphic novels. They only contain segments of a story released over time. Many graphic novels compile several issues of a popular comic book, such as Alan Moore's Watchmen and Neil Gaiman's The Sandman.
... For those interested in history, Marjane Satrapi's Persepolis is an autobiographical account of her childhood in 1970s Iran, while Art Spiegelman's Maus: A Survivor's Tale tells the Holocaust survival story of the author's father. Teens would enjoy Brian K. Vaughan's fantasy series Runaways, and younger children might like Babymouse, a popular graphic novel series following the antics of an imaginative mouse.