My "wall" is a flannel backed table cloth suspended from the closet doors.
The downside is that it must be removed nightly as my husbands clothes are behind the doors, but I have a large cardboard tube so I can roll it up until I'm ready to work again. {Note to self - roll more carefully next quilt so that I don't have to repress all the blocks again.}
Once the quilt is pieced together, I can then hang it from the hangars without the table cloth for things like auditioning borders or photographing it. I've also used the closet doors to support a quilt that I basted with water soluble thread to "unbaste" it with a spray bottle as I had too many crimps and creases in the back after the initial basting.
I wish I had room for a more permanent/durable wall, but recently inherited quite a few oil paintings, one of which will take up the wall I had originally designated as a design wall. But that wall would have been much harder to work on as I needed to place a table and shelving along it anyway.
I'm quite happy with this set up. Much more so than when I laid the table cloth on our bed (risk of Corgis settling on it). Floor was never an option due to lack of open space and Corgi wrestling matches.
Cheers, K