I am in general against declawing- its pretty unnecessary in most cases in my opinion. I would at least give training your cat not to scratch a really, really good shot before even considering it. I got a kitten in December last year, and there are 2 things that she scratches in the house- her scratching post and an old couch in my sister's room. I think she started scratching the couch because thats the room she is in the most- so shes kinda marking it as hers. It was easy to train her not to do it to anything else- have a scratching post (or whatever you want them to scratch) in a place where everyone can see it- ours is in our lounge next to the tv, apparently cats like it when the thing they scratch can be easily seen, im not sure why, i assume its something to do with marking the area as kitty's and making sure all other animals/kitties know it. Reward them when they scratch the post (i cooed at her and stroked her and told her how gorgeous and wonderful she was and played with her when she was done), and if my cat started scratching other furniture then i simply said "NO" loudly and clapped my hands so she stopped and ran off, or do that and put her paws on the scratching post (i didnt run her paws on the post since i have read thats not very pleasant for cats). My cat learnt pretty quick that (a) scratching the furniture causes loud scary noises, and (b) scratching the post gets lots of praise and love and attention.

Personally, what i also think is if you dont want your furniture scratched, dont get a cat It takes a while to learn, I was lucky because i was home all the time for her first few months of life so i could catch her almost every incidence of scratching things she shouldnt and correct that behaviour. If you arent going to be able to do that and dont want to risk your furniture being scratched, dont get a cat basically. Just my opinion, but scratchs and shredding things is part of the joy of being a cat owner

But i am biased, my cat is a polydactyl, and has 2-3 extra toes AND claws on each foot