I sleep with just one pillow, but when i am sick or feeling tight in my chest, I use my pillow plus my wedge (i got it from harriet carter magazine, or harrietcarter.com). its called a large bed wedge (19.95 + s/h). I purchased it to use to for posteral (sp?) drainage during CPT, but it works well for propping myself up for sleep.
I sleep on my back or sides, depends on how my breathing is. When I am sick, I breathe easier on my back but I rather sleep on my side (right side preferred since my port can get in the way on my left side). I rarely sleep on my stomache now. If I sleep on my stomache, when I wake up my chest hurts and I can hardly turn my head because my neck is so stiff. Whatever position I fall asleep in that is ususally the position I wake up in. I barely move when I sleep.