I sleep on my back, side(s) and stomach, switching back and forth throughout the night.
I've been using a size Med. NeoAir pad (add a GG thinlight pad when it's cold). This seems to work as well or better for me than other inflatable pads in the past with the benefit of being lighter and smaller to pack down.
Recently, I've started to use a quilt rather than a mummy bag. I'm pretty happy with this as the quilt stays put and I roll around inside of it. No more getting wrapped up in the bag or waking up feeling suffocated with my face in the hood of the bag. Currently using a Katabatic Sawatch.
For a pillow, I've gone back to the drawing board, so to speak, and am using extra clothes stuffed together in a sack until I can find a more comfortable (but still light) solution. I played around with some of those inflatable hospital pillows like BPL sells, but found them to be uncomfortable or hard to keep in place. I haven't tried a more substantial inflatable pillow like the Montbell or Kookabay yet, but might in the future. I usually stomach sleep with my head resting on my "pillow" propped up on one of my arms.
I'm intrigued by the down pillow a couple of you guys mentioned too.