If you have a good carpet retailer nearby they should be able to give you good advice. I am going to be replacing the carpet on my basement steps soon also and have the same issues. You're right about not getting standard plush. But the salesperson at the store I go to has pets too, and I know she'll have a good suggestion. I'm definitely getting cat puke color this time around. :-)

When you go to the carpet store ask about industrial carpeting. The kind used in hotel lobbies and theaters. It’s what I put on my stairs 20 years ago. I have had 4 cats at various times and they payed little attention to it as their were no loops to get their claws into. Very easy to clean up messes as my husband will attest too since he was the one that spilt chocolate ice cream on it.

Why is hard flooring not an option? It is best for allergies and the cat issue. All edge to edge carpet has a built in demise, a hardwood or engineered or even LVP will outlast it by years and years.

Look at the commercial carpet section if you must have carpet

@jalarse @JAN MOYER thank you, I'll ask about industrial carpeting. And I'll definitely be trying to find a good knowledgeable retailer, we're just at the very beginning of figuring out what to do.

We don't want hard floors for a few reasons, but primarily honestly, we just prefer carpet upstairs, and are willing to deal with the negatives of carpet - I know each type has a con. I'm just trying to determine what the best of the bunch might be for us, and I'm wondering if anyone has experience.

Everyone has a preference. Just saying it's the worst for allergies, and there is no carpet that lasts really well on a second floor. Why? It's where you are most often in BARE feet. Your feet leave behind the oils, which then attract the dust, ( dust is mostly you, and dead skin ) and then you grind in that infamous "traffic pattern" every time you travel the same path . Stairs, closets, the route you take to the bath. It's also the ( 2nd ) floor that gets a bit less vacuuming than the first floor. Which makes it even worse.

But again......it's preference. Area rugs can be nearly room size or just where you step from bed, and are in the long term? A whole lot easier.