You can use the same ideas for reading groups for teenagers as you use for adults.

Diana Tixier Herald, @genrelibrarian, regularly tweets about her YA bookclub - #bistrobookclub

The following questions are used to review books for ALA | Best Books for Young Adults and they might help you with getting discussion started.

How well did the author capture your attention?
How clear was the author’s theme or message?
How vivid were the details?
How well did the book build in intensity?
How clear was the resolution?
How well did the author’s language add to the book?
How well did the writing match the book’s intended audience?
How well did the characters develop?
How effective was the author’s voice?
How well did the dialogue match the theme and style of the book?
How enticing was the cover?
How enticing was the jacket blip?
How much did you enjoy reading this book?
How highly would you recommend this book?
How likely are you to reread this book?
How well did this book match your morals and ethics?
How heavily did the influence of others affect your choice to read this book?
How memorable was this book?
How 3-D and alive was this book?
How creative was this book?