I buy the 2nds and light soiled (clean up like new) 100% cotton bedspreads from Plej's (kind of like a big lots for bedding) they are great, alot more absorbent than sheets and only about $3.50 for the doubles. I keep at least three on hand so I can change them out and have a clean one at all times. I also find that if you throw an extra throw over the back of the couch it will fool the ones who think they should try and get under the cover when your not looking. I also keep 4 couch pillows on the couch leaned against the back so they can do the hide and seek thing.
I also have a small (single bird) cage (door never closed) next to the couch on a fish tank stand with one hammock and one tube and have the bottom covered in their litter box pellets and they use it to do their business, 99% of the time (raisins and what not) and not my couch. That cage also doubles as the travel cage if one has to go to the vet. The two little girls think it is their vacation home and have laid claim to the hammock and tube. I also keep water and dry food in that cage so they can snack while they are out. And they like hanging out on the top of that cage also.
I have never let my rats on the floor. I have found if they have never been on the floor they don't want to get on the floor. They have a 3 story 5 cage, (very large) interconnected complex (remember there are 11 of them) and it sets on top of a big (long) lane cedar chest and during the day I usually leave the doors open on various cages when I am home but not wanting to take rat time. That way they run through and in and out of the cages. I figure it gives them less of a caged feeling. It is set up with one large cage on the left bottom for litter boxes, the large right cage is food, food, food the two second story (right and left with a “breezeway between”) are sleeping and grooming, and the very large 3rd tier cage is also sleeping, with all cages having hammocks and tubes. Also all sleeping quarters get daily changes of cotton rags. They never try to venture any further than their own space, so they must be happy. Except to set in the window at times and chew on the cover that blocks their top cage from the window. When ever any of them are awake and rowdy they like to hang out on the very top cage and keep an eye on everything. It also makes them less rowdy in the evenings when we have more time to hang on the couch. Still doesn’t make my crochet time any easier in the evenings, until they settle down a bit. They also like to hang out on top of the (litter box cage) next to the couch and take turns at climbing on me when I am sitting on the couch. Which is much easier on me than having all 11 trying to get attention all at once.
Anyway I have rambled on and all you wanted to know about was the couch cover…