Gone Girl by Gillian Flynn is the book I've seen on every summer reading list. When I read the summary on Amazon, it sounded like every other thriller I've read. Regardless, I decided to give it a try. It was fantastic. The writing is sharp and witty. The pace is fast and there's a fantastic twist. You'll have a hard time putting it down.
The Snowman by Jo Nesbo is one of the best Inspector Harry Hole novels written. I enjoy a good Norwegian crime novel and this series fits the bill. Harry Hole is a wonderfully flawed character who always does good but has to overcome his demons on a regular basis. The mysteries he unravels are complex and you're never sure who's the villian. For me, that makes any Jo Nesbo book interesting.