I have created 47 bookmarks with 2-4 books per bookmark. I have colour coded the bookmarks according to their series or author. They also include their Lexile levels from the the Literacy Pro.
The reason for this is to encourage students to become engaged in series of books. This then means they can concentrate on the story and not be continually being introduced to new characters. They can then become engrossed in the plot, story line and the complexity of the language.
I hope this helps with your reading programs.