For us, our friend the Wedge (photo, right) was our regular companion, permitting me to lie comfortably on my back with a lifted bottom and allow Robert free movement on his knees. This has especially helped us during episodes of back injury, knee pain, and arthritis flares, as well as delightful encounters when we have no aches or pains. Using a firm, specially shaped cushion also provides optimal comfort and convenience for enhancing lovemaking with a favorite sex toy. (Our personal favorite, as you must know by now -- the Eroscillator, the only sensual product endorsed and recommended by Dr. Ruth Westheimer.)
Have you experimented with different types of pillows and cushions for comfort and pleasure? Let me know your favorites!