This is Marshall, if you don't recall him. He's taken a bit of a backseat since the new puppy rolled in on June 10 (also Riley's birthday).
We've never declawed him (and never will and I'd be more than happy to tell you why that's an incredibly horrible idea if you'd like). Every once in a while he think it's a good idea to scratch the arm of the couch or one of our chairs. He usually stops when he realizes we've busted him, but we can't keep him away from everything when we're gone.
We recently had the opportunity to test out Comfort Zone® with Feliway® for Marshall. I'd had luck with the dog version with Riley back in the day, so I was more than happy to try this out with that cat. We could have used it more when we first moved into the new house, but he eventually got settled back into things.
The way it works is it emits this vapor that settles the animal, in this case Marshall, down a bit. It doesn't cause anything to smell or lead it to have any effect on anything else. Neat, huh?
He's definitely slowed down on causing any damage to furniture, which is awesome. Especially considering we have a new couch. In the month or so that we've had it, I'd say it's definitely working. We're lucky that he's never been much for peeing anywhere that's not his litter box, but if your cat has that problem, this stuff will work for you.
Comfort Zone® products should obvoiusly not be used until you're sure your cat or dog aren't having medical issues that need to be treated. Their Facebook has all sorts of good stuff to keep on, too.