My rabbits could care less about phone books, cardboard tubes, or sheets of cardboard. They're going to chew no matter what you use, and sprays will only drive them to chew something else like carpeting. The trick is to find what they really LIKE to chew best, and leave that around.
My bunnies love compressed timothy hay blocks, we leave them everywhere, near their food and water, under the dining room table, just anywhere they hang out. Another cheap alternative is those $1 beach mats made of straw. My rabbits shred those right up,and while cleaning up is a little bothesome, the love it, and it's not as bad as the thought of having to buy new furniture.
As far as the sofa is concerned...You may have to get plastic slipcovers. Fang and Smokey didn't like the feel of plastic covers, they kept sliding off, so they avoided a plastic cover. We don't have plastic now, because my husband is always in the living room with them, supervising his 'minions'.
Large cardboard boxes work for me (especially if you put something valuable of yours inside), bunnies seem to want to get their owners personal belongings. Just leave the closed box lying around , and they'll knaw at it. My Smokey is also toatlly into TV Guides, especially those little postcards inside for sending back to order stuff. The TV guide, and most newspapers and paper products, are printed with soy ink, so they're not harmful to bunnies. Oh, and if you do buy a new sofa, make sure you leave the sales tag ON when it's delivered! My rabbits LOVED the tag, it took them three days to completely destroy it!
They also adore potted palm trees. Palms are fibrous and woody, and are great for little nibbles. Make sure you VERY CAREFULLY check which type of palm tree you get, certain ones are harmful, check with your doctor. HouseRabbit.org also has a great list of plants that are safe or harmful to bunnies, check them out.
No matter what you do, you'll have to resign yourself to the fact that you are going to be sweeping or vacuuming up shredded up pieces of something every day, and I personally think it sucks, but the alternative is overgrown teeth, and an expensive dental bill to have them cut. You're going to have to see what they personally love to destroy most, just don't give them anything that looks like power cords!
Also, baby gates or pens everywhere will help. it's annoying, yes, but peace of mind is a great thing. Our TV and computer areas are 'restricted with baby pens all around. We just ordered a glass fronted tv stand that will hold everything inside and keep the wires completely out of reach, yet it's really pretty, and inexpensive too. When rabbit owners shop for furniture, they need to think about what will be bunny proof. My bunnies don't like pine,therefore most of my furnishings are made from it. Wrought-iron bottoms for tables and chairs are great too, no knawing, and my rabbits play with them like a jungle gym!
Good luck, and keep us posted!