I have a dozen or more quilts stacked on a bed in my guest room. I have nothing separating them and did not see a need to do so. I use a lot of bleached muslin and love it to back quilts. I don't pre-wash it either. I do use it washed however and set it with pot ash if I am going to die the fabric. That of course is another topic all together.
It is easy to show off quilts this way or move the majority if having a guest over night.