Insomniac's blog

This question is hard to answer. The capabilities, maturity, and education of each young adult pupil needs to be taken into account. Some middle schoolers and high schoolers are capable of reading novels and stories that some adults may not be able to read. Others may not be able to read even YA books and may have to remain with juvenile books for awhile longer.
For proficient readers, I would say let them choose to a certain extent. A teacher should perhaps recommend certain titles, authors, or genres for their gifted and talented pupils, but let them choose books that they believe will challenge them.
For the less proficient reader, teachers also need to guide them in choosing books, but the teacher needs to understand the pupil on a personal basis to understand their capabilities. For the average reader (those reading at their grade level), teachers need to still provide choices based on their level of ability.
Some YA readers may be very fast readers, but lack comprehension. Books that force these readers to slow down may be a good choice as well as exercises like the "picture it" thing we did in class may help these readers with comprehension.
I do not believe in the so-called banned books idea. Censorship should be a personal decision between the pupil and their parents. While certain books may be to difficult for YAs to grasp concepts (such as Paradise Lost or the Satanic Verses ), books like The Scarlet Letter or Huckleberry Finn are not too difficult to understand. The main reason for parents to object to these books are because of language and situation. As a parent, I can say that children hear and see a heck of a lot worse on Sunday evening television than what they will find in most books!
So, acceptable literature for YAs to read varies. There are so many different types of learning styles and readers out there that to classify what is "good" and what is "bad" is simply much too difficult on that broad of a level.