I have a friend interested in jumping in to the genre.
Looking at the the graphic novel that I have, these are the following books, publishers:
1. Persepolis by Marjane Satrapi - first published in English by Pantheon Books, a division of Random House, Inc and Jonathan Cape
2. Fun Home, Are you My Mother, The Secret to Superhuman Strength by Alison Bechdel - Jonathan Cape
3. V For Vendetta, Alan Moore - Vertigo
4. Watchmen, Batman: The Killing Joke, Alan Moore - DC Comics
5. The Middle Ages: A Graphic History by Eleanor Janega and Neil Max Emmanuel, Icon Books
6. Maus I & II by Art Spiegelman, Pantheon
For background in terms of the structure of a page (panels, frames, speech/thought balloons, text, images, word balloons and sound effects, etc.) I read the following (but part of a MA in Eng Lit module):
1. Graphic Women: Life Narrative & Contemporary Comics by Hillary L. Chute
2. The Cambridge Companion to The Graphic Novel, ed. by Stephen E. Tabachinick.
I love graphic novels, never read one until my MA, but absolutely fell in love with them - so much so I wrote a comparative essay on Alison Bechdel's Fun Home and Virginia Woolf's Orlando.
I also remember an episode of Pop-Ups in maybe September or October. The guest, a children's publisher, promoted a recently published YA graphic novel about travel in, I think, Mexico. She said she wanted to publish more graphic novels (I can't remember her name, but could find it if you can't).