I've put the Sticky Paws tape on mine. It's helped tremendously. Now only one likes to even sleep on the couch, and that's not an issue.

I've also bookmarked some leather repair stuff, not sure if it works, so haven't ordered it yet. My sofa and loveseat even have a PU coating on them, and my one girl just got her little claws in and started kneading away on the arms! I thought I was going to flip out!