Ideas for a new and improved cat room?

It is wonderful that you are doing so much for these kittens and cats. You didn't mention scratchers, like the typical cardboard ones. I would have several, even though your cat tree probably has sisal. Cats love to jump around on things, especially if they are stacked. Would it be possible to have shelving at different levels along one wall? Or else cubes that can be stacked at various levels, to allow them to jump and play on, and even play hide and seek. I have cardboard boxes for mine to jump in and out of, and one with a hole in the side that they use as a cave. Very popular.