Recommended mattress for my wife and myself.

My wife suffers from COPD, and sleeps with a pillow to 'prop' her up; she also has osteoporosis in the bottom of her spine, so should lay with her spine straight. She sleeps on her back, is 5 feet 2 inches tall, and weighs less than 7 stones. I am 5 feet 6 inches tall, weight 12 stone, and sleep on my side, but turn a lot in my sleep. Which mattress or mattress /base combination would you recommend?