I got a heavy, solid (70lbs) cat tree some years ago and even if all three cats leapt on it at the same time, with a combined weight of 27lbs, I don’t think it’d budge. It might jolt, but it ain’t fallin’ over. I don’t really remember how my girls reacted to it when I set it up, though I do have a picture of that first night with all three sitting on their own perches.
A couple of months ago, we ended up with a new kitten, strictly in a foster basis, and it took her a little while to figure out what the tree was for. She didn’t seem to understand how to climb it. We’d place her in one of the perches and she’d just sit there, maybe even fall asleep, and I think she even needed help getting off the first couple of days. But now she’s a crazy little monster who vents her excess energy on that poor tree. Leaping, climbing, hauling and falling, and of course, sharpening her nails. She also seems offended if another cat is already on it. She’ll harass said cat, swatting and poking, until the cat finally hisses and books it, taking a flying leap on a nearby couch. To be fair, Marcy’s not great with the girls to start with (seriously, I don’t know if she ever got socialization lessons, because she does NOT know how to speak “cat”), but she’s especially mean when it comes to HER tree.
Look around at as many trees as you can find, and don’t even rule out ordering one online. I got mine from a guy who makes them himself and sells them off his website, but I got mine off ebay, when he used to sell them there (he’d start it at $1, but the trees were hot commodities and never sold for less than $150). I got mine for $155, shipping was, I think, $40-something, and I can’t remember the customs fee (it might have been $44, or it might have been $70-something). All in all, I still think it was a great deal. It’s 6 1/2 feet tall and 70lbs. I had to put it together (the bottom half was already set up, it was the upper portion and the posts/platforms that needed to be assembled), but it was fun. Got it 7 years ago aside from some fraying, it still looks good. I work at Petsmart now and I can’t help but look at our trees with snobbishness. They’re overpriced flimsy wobbly things. Same with the trees at other places.