Earnest, my Great Dane/Lab mix, eats dog beds. My solution was to buy him (at the thrift store) a toddler bed, and put it in my bedroom. That's his bed, and he often sleeps in it at night. If it's cold, or he wants company, he'll come stand by my bed and breathe in my ear until I tell him ok, and make room for him. During the day he spends most of his time on "his" couch, I have a big 9 footer that he, my son, and I can all fit on.
Phyfe, our Mastiff/Saint Bernard mix, prefers the floor when he's upstairs, and he has his own futon downstairs in my son's basement bedroom.