Seriously, you won't go wrong with sailrite. This foam I purchased last year, but have not used it yet. It is excellent for settee cushions.
Dry Fast Foam Open Cell 2" Thick 48" x 72"
For a sleeping surface just add 2 inches of memory foam to the top. Make sure its breathable.
For my money, Ultraleather Brissa solie is for me. Just havene't purchased it yet. As Paul said, its breathable, resists mildew, cleanable, and looks great.