The main rug my cats use is laying on top shelf of an old, very stout, wire rack once used in a grocery store. The shelf measures 2ft x 2ft & the cats' food & water is up there where the little dogs can't reach. The cats have room to lounge on their rug, which fits perfectly, & watch the birds out the kitchen window. I have washed it a few times & hung to dry, easy to do.
Also there's a rug in the wire kennel crate, on the rare occasions we use it, like going to the basement in severe storms.
Some of them like to lay on the carpet floor, most prefer higher places, but they all like to scratch on carpet & I don't see any harm in it.

Pros: comfortable

Cons: none

I used many rugs throughout my house. The ones that are the most useful are near and around my litter boxes. It helps keep litter from being tracked all over. Cats also love to sleep on a soft rug and that helps keep hair off your furniture.

Pros: Help keep litter from being tracked, hair off furniture

Cons: Some rugs cats like to scratch on and wreck

I have several throw rugs by the backdoor and kitchen sink. They get a lot of wear and there is a loose thread that my Daisy likes to paw at and attack. Other times the cat will be sitting or sleeping on the rug. She knows where the soft stuff is in the house!

Pros: Soft and comfy for the cats

Cons: never be the same

We have rugs in front of the doors, to help with drafts. Sometimes the cats will decide to burrow underneath. And then leave the rug a lumpy mess for you to trip over. We have old rugs that we've put up on higher furniture for them to lay on, too

Pros: warm

Cons: none

We use throw rugs around the litter boxes and inside the cat carrier in the winter. It seems to make things a little warmer than just a plain towel. Having them around the litter boxes helps keep down the amount of tracking of loose litter.

Pros: Clean

Cons: none