Like most districts, my district has a required reading list for each grade level, but the list has numerous novels from which the teacher can choose. There are specific books on that list earmarked for the gifted and talented program, pre-AP, and on-level students. For example, the on-level students read The Outsiders when the GT students are finishing up The Taming of the Shrew. When considering choosing a book, I would always opt for picking a book with a higher than grade level lexile ranking, just because my district is very AP oriented and I want to prepare my students for high school English.
One of the great freedoms, however, is literature circles. I use literature circles in my classroom to introduce those higher (or lower) level books for my readers of varying abilities--and since these are smaller groups, I can bring in more modern or edgy texts that build reader interest.