Embracing Contemporary Literature
While it's true that AP Literature is primarily concerned with the classics, they aren't its only concern. In fact, they've referenced plenty of pieces of contemporary fiction on their exams, including The Handmaid's Tale by Margaret Atwood, American Pastoral by Philip Roth, All the Pretty Horses by Cormac McCarthy, and The Namesake by Jhumpa Lahiri, among others.
There are many benefits to including a piece of quality contemporary literature on your AP English summer reading list. Firstly, your students might really appreciate it. The decline of reading is well documented, and even your brightest students probably aren't doing it enough for pleasure. Their course loads and extra curricular activities take up a huge amount of their time. I hope you'll agree that we don't want them to leave high school thinking that their only choices in literature are dense classics (however impressive they might be) and frivolous pop fiction, like Twilight. You have the opportunity to expose them to another category of great books: the contemporaries. There are certainly plenty of excellent novels written every year; introduce your students to one of them.
Another benefit of including a contemporary piece on your summer reading list is that it will force your students to do their own analysis. Unfortunately, due the abundance of study aids available online and in print, some students don't even read the books assigned to them. Instead they read summaries and analysis on sites like SparkNotes. If you pick a newer novel, you may be able to take away their crutch, and they'll have to do their own thinking. Keep in mind, though, that if this is a big concern of yours, you should check to see if SparkNotes already covers the work you're considering assigning. Also, if SparkNotes does cover the book, read the SparkNotes version before you grade the assignment (or create an assignment) and bring your classes discussion and focus to the aspects of the text that were not covered. This will teach your students that they cannot just read SparkNotes early on. The Handmaid's Tale and All the Pretty Horses fall into this category.
Here are a few other AP-worthy contemporary texts that you might consider:
The Elegance of the Hedgehog by Muriel Barbery
The Known World by Edward P. Jones
Extremely Loud and Incredibly Close by Jonathan Safran Foer