I have one of the expensive trees from Petco and an Amerkat tree from gopetclub.com. I love the tree from Petco--sturdy as all get out and I can put it anywhere. The Amerkat tree has to be against a wall and is not nearly as sturdy. My cats are ~average sized females and it seems to work ok, I can't imagine it for large cats at all. The Amerkat trees have fleece rather than carpet.
Angie
Angie