I always turn my head to the side in turbulence. My theory is that the body is used to up-down (bumps) and fore-aft (gas/brake) forces from driving in cars, but side-to-side or yawing motions are what is out of the ordinary and make me ill.

By turning my head to the side, the side-to-side of my head would have to be acceleration/deceleration of the plane, which typically isn't what happens in turbulence. The up-down is still there, but the plane yawing turns into front-back acceleration to my ear canals, where this motion is sensed, which isn't a problem.

Whether that theory is correct or not, it certainly works for me. I turn my head 90 degrees to the side and the turbulence sensation is immediately reduced, and motion sickness sets in much more slowly.

I've heard both front and middle for the least turbulence, and a search of the google turns up an equal number of both answers. If the wings are at the center of pressure, up-down turbulence should displace all seats the same, assuming a rigid body. With some flexibility, I can see both ends displacing more than the center. Turbulence causing the vertical stabilizer to move would cause more yaw front and rear than the center. And turbulence causing the horizontal stabilizer to move could either cause movements at both ends or cause the most movement at the rear and the least at the front.

Either way, the rear is bad.