Gone Girl, by Gillian Flynn, will leave your book club with plenty to discuss. There is a lot happening in this novel. There are a lot of twists, and you may even find yourself debating the actual marriage of the two main characters as well as the mystery of the wife's disappearance.
American Gods is easily my favorite Neil Gaiman book. There is no way I could sum up everything I feel about this book, so I'll just tell you that your book club will surely have a heated debate about this book, and close this part with my favorite literary line ever: "You're so full of shit, I'm surprised your eyes aren't brown." - Odin, from American Gods.
The Memory Keeper's Daughter, by Kim Edwards, takes place in a time when kids with disabilities are treated as less than, simply because they have a disability. I won't say much more than that. I will simply tell you that this novel will break you open and leave your book club with more than enough to discuss after you read it!
The Help, by Kathryn Stockett, is always a sure fire hit with book clubs. There is so much tension, and anger, and so much to discuss about the racial inequalities that occur throughout the book. You'll find yourself simultaneously loving and hating this book, and your book club will have plenty to talk about!
I picked two Gillian Flynn books this month, because they are both so good. Sharp Objects, I thought, was slightly better than Gone Girl. It has mystery, some mental health issues, and a cast of characters that will draw you in and make you go "Oh, god, no what just happened?!" Your book club will love this book and it will keep you talking for sure.