I just got finished reading about a Qantas flight making an emergency landing due to turbulence. Thirty of the passengers received injuries and fifteen of them are serious injuries such as broken bones and lacerations. This occurred primarily in the rear of the plane. I can't believe passengers were thrown around that hard from turbulence that they received injuries...
Here's a tip: Sit as close as you can to the wings. Think of it like a seesaw. The opposite ends have the most distance of travel while the fulcrum (wings, middle) area has the least amount of travel.
Here's a link to the article:
Turbulence forces emergency landing