This is a super old post but I just saw it and thought I'd comment! I have a lab whose pretty big, and this orthopedic bed from Ortocanis we both love! Big fluffy beds can usually do more harm than good. Having a firmer bed will protect the joints better and a good bed will evenly distribute your dog's weight.

Both of our beloved canines are now gone, but we settled on a Better World Large Orthopedic Dog Bed for our lab. He loved that bed, and it was very comfortable for him. It is about 6 inches thick and did not flatten though he weighed over 100 pounds. The cover is very easy to remove and wash. It is made in the USA (I did NOT want anything made in china) and they donate 10% of their profits to the Humane Society.

For my larger dogs I use two beds each. I have an orthopedic bed topped with a donut bed. They really like the donut beds as far as resting their head and paws on the perimeter donut part, but the inner part was thin and didn't give enough comfort or support so I use two.

Since I started doing that I will often see them sleeping on their backs when I wake up, the very picture of comfort.

i got 2 giant beds from dogbed4less.com. they are memory foam, come with an inner waterproof cover and a nice, heavy canvas cover for the outside. the beds are memory foam and when there is no room on the couch for me, i often lay on them. very comfy!!