My cats are totall azzholes and have just ruined my precious, beautiful Macy's couch in my living room. I'm really glad I got it secondhand for $400 because after three years, the upholstery is total garbage. It's this nubby textured fabric that is apparently awesome for a kitty scratching post. It's just effing shredded. And light cream w/ a tortoise shell who thinks it's the best cat bed ever? Awful. (The other two currently think the crib is the best cat bed ever)
I've found that they don't scratch anything with a smoother texture, like a cotton twill. (Side note: I looked for slipcovers and they are all made for puffy couches and not vintage looking skinny couches and I have no inclination to attempt a major reupholstering job when the frame isn't in good condition anymore either).
So, do cats not like scratching leather? Fabric recommendations? I found an Ikea leather couch on CL for $125 that I'm considering or a seriously cheap $250 cotton twill couch from Target.com. I'd be tickled pink to get 3 years out of a couch, since that's apparently the life span of couches in our house and it's not worth buying a $1k sofa that a toddler may draw on some day. I don't even care if it's comfortable, it just needs to look presentable since it's the first thing you see.
Oddly enough, we have the exact same sofa in the family room and the cats don't scratch that one.