Cats, claws and lovely furniture  

Water Bottles
I would never have a cat declawed and can't even imagine the blood that would flow if I tried to subject my cat to claw covers.
What's worked for me - yelling "NO" like the earth is about to end at kitty when she tries to scratch your nice furniture - then while kitty is still in stunned shock at your sudden pits of hell yell, walk over to their scratching pad and lovingly coach them to have there way with it. It's worked well for me, after my cat attempts to scratch my furniture and I then go over and scratch on her cardboard pads, she always walks over and scratches the hell out of the cardoard like a good kitty.
If the yelling doesn't work, the water bottle will. Just keep a handy spray bottle by your side, any time kitty tries to scratch yell "no" and spray with some water. It will get to the point merely reaching for the bottle will do the job.
My kitty's attempts at shredding my dux couch have been reduced to a mere attempt or two a month and its not really because she wants to scratch it but because she damn well knows that's a sure fire way to get my attention if nothing else will.
The only thing I should add is my kitty does get to go romp outside when she pleases (has nice woods to play and hunt in) so she gets out a lot of her energy and scratching behavior there. When I first had her and tried to keep in her indoors that bottled up energy was harder to contain in positive ways.
(Also there tends to be more problems with cats that are cooped up alone all day in small apartments. If your cat is spending lots of times without you in the apartment sometimes the scratching is an aggressive way of telling you they need more love and attention.)
Also, very important, to make sure you have a real scratching pad that they actually like and use. I've had no success with those pole things or carpet pads. However the boxes with the sides of cardboard strips in them - I've never met a cat that didn't love those and use them regularly. Kitties have to scratch and keep their claws filed - so its absolutely necessary to provide them with an outlet. (No outlet, means your furniture is cruising for a bruising.)

Acceptance
You, that scratching will happen and Kitty with the fact that she WILL have her nails trimmed. (Trust me they do get used to it)
Go see your vet and learn the right way to do it and then take up yoga so that you can calm down when the little darling has added anotehr set of picks and pulls in your Womb Chair's wool boucle'. That was my method of coping...
Oh and get some of these...cats love them and they're much easier on the eyes than those carpeted monstrosities. The tacky printed edgins are easily removable leaving the nice plain corrugated.
http://www.catclaws.com/

don't give up!
cats are particular in what they like to scratch (and preferences are individual to the cat).
some like sisal, some like carpets, some like cardboard, but make sure to try all angles (vertical, horizonal, etc). you also might try rubbing your kitty's claws on the surface directly, and praising him.
also, sometimes (depending on the cat) a sprinkle of catnip on the scratching post works wonders.
if all else fails, I second the recommendation for yoga. 😉

ps
I tried this product, with great success: the SmartCat Cat Climber-- it hangs over a closed door. pros are that it's somewhat attractive; cons are that it's expensive, and you don't know if it will work before you try it. but my kitties really loved the sisal (they also love my oriental rugs, a habit I've not broken them of).