In the same way that it's hard to find stand-alone novels for the die-hard series reader, it's hard to find stand-alone graphic novels for the graphic novel series reader. In my 4th grade classroom, I work with series readers of all kinds to venture into non-series books. One is not better than the other, it's just that they each take some very different reading strategies.
Kids will be drawn to Bad Island by the monsters and the fight scenes and the sight gags, but it's a pretty complicated story that I will want to make sure I conference with readers about when they've read it or are reading it.
I will want to know what they think of the characters and the way they change or don't change. This is the story of a dysfunctional family that goes on a sailing trip that only the dad wants to do. They get shipwrecked in a storm on an island that turns out to be a monster that was exiled from another world long ago. The dad and the brother in this story change and grow in satisfying ways, but the mother's character is pretty flat, and the little sister is just plain annoying and weird all the way through.
Readers need to know how to attend to the back-story of the monster and how he came to be an island in a different world. This other story is told on pages with a tan background, so readers of BabyMouse who know that the dream sequences are always in pink should be able to make that connection. But readers also need to be able to put together the clues from the back-story with clues from the family's story to figure out how the two connect.
As always, reading a graphic novel is way more than just looking at pictures. If you don't often read graphic novels, but your students do, you need to make a point read some and think about the strategies you are using as a reader, and the ways you can teach into the reading your students (sometimes/often) love best.
Check out Adventures in Graphica by Terry Thompson for more ways to use graphic novels in your reading workshop.