I understand that graphic novels have a bad reputation of being a cheap and lazy sort of book but I disagree. I read my first graphic novel in junior high. Our school librarian had the Elfquest collections (I am not positive they were called graphic novels in that day). These were books that basically housed several comic books that completed most of a story line. I loved them so much I bought several Elfquest comic books. Then the comic books went away - I am not certain they were no longer being made, I just could no longer get them. So with that, my interest in comic books went away.
While I was in college, the movie Schindler's list came out. There was a big display of like-minded books at the bookstore and one of them was Maus by Art Spiegelman. If you have not had a chance to read the two Maus books he wrote - find them. Art Speigelman uses the "comic" medium to tell the story of his father's experience as a Polish Jew during the time of WWII and a little beyond.
I can't say it threw me back into the world of the graphic novel but I did manage to find a novel sized edition of the Elfquest books. That book sat proudly with my Maus books on my bookshelf for my son to discover years later.
It was my son who actually pulled me into the world of the graphic novel and it didn't hurt that graphic novels were making a comeback. He loves series books such as Inu-Yasha and Pokemon (in fact last year he had the flu and was sick for a whole week, during that time all he read was graphic novels - we were begging the librarian for more and more because he was reading them so fast).
What I have found is that graphic novels are just a different approach to a story. You can still find the typical superhero novels but they are so much more than that. There are historical graphic novels (some fiction, some non), classics in graphic novels (from horror/mystery to children's classics), romance, adventure, and anything you can think of. So many popular books are being redone as graphic novels.
Graphic novels can be a great gateway into reading.
For younger readers I recommend:
Cirque De Freak by Darren Shan
Courtney Crumin by Ted Naifeh
The Good Neighbors by Holly Black
Vogelein by Jane Irwin
Marvel 1602 by Neil Gaimen
Artemis Fowl by Eoin Colfer
selections by Shannon Hale
Selections I haven't read yet for young readers:
Warriors by Erin Hunter
Alex Rider by Anthony Horowitz
For older readers:
Maus by Art Spiegleman
Watchmen (you really had to live during the 80's to understand this book)
Persepolis by Marjane Satrapi (the 2 novels she wrote were turned into a movie)
Anita Blake books by Laurell K Hamilton
Mercy Thompson by Patricia Briggs
Pride and Prejudice and Zombies (I tried reading this book but it was awful. However it's really popular so I added it here)
One's I haven't read yet:
Dresden Files by Jim Butcher
Gunslinger by Stephen King
Circle trilogy by Ted Dekker
Odd Thomas books by Dean Koontz
As you can see there is a large library of graphic novels out there and more and more keep coming. These books we found at our local library. Because they are such quick reads I don't purchase many graphic novels. Those we have purchased my son has read over and over. Manga books (ones from Japan or in the style of) are often backwards to what is "normal" in America. They are a little tricky to read but still well worth it.
I even found a parenting book in Manga style and will talk all about it when I have read it.