I recently purchased two cat trees - during my quest I did a ton of looking at a ton of sites. I ended up getting
this short one &
this larger one. Both were purchased from Petco. They carry two versions of the Armarkat trees - I wanted
this larger one but it wouldn't be back in stock for several weeks.
Here are pictures of my kitties on them.
I was on a budget, I wanted the most bang for my buck. I found while Amazon.com had pretty good prices, sometimes you didn't know what brand they were & with free super saver shipping it would take 3 weeks to arrive. I've seen both the Armarket ones Petco carries - a family member owns the larger one & I had leaned on the one I purchased on a previous visit to Petco.
BTW - I have 11 cats in the house now, and so I often have a whole tree full of cats. Some like the little "house" part of the tree, others like the perches, and one kitty likes the very bottom shelf. I'm not sure if all 4 of yours would fit comfortably on the same tree I have or not - I've had 5 or 6 on there at once.