What I really like is the pile of books, and how it's still standing with three cats right there, and your big dogs too!

I've got a really old one that breaks all the rules, and if it wasn't shoved in the corner between the refrigerator and the wall it would probably fall down, but my household of cats has enjoyed it for at least 15 years. They also like the little hidey-holes in the bottom, and running into the bottom opening, up through the base and then up two shelves to the top--they really look energized after that!

Steve Dale has a neat video about environmental enrichment for his cat, Roxy, where he tosses treats into Roxy's favorite places on cat trees around his house for her to "go on the hunt":