If you have any DIY skills at all it's really not that difficult to buy pre-made replacements skins from Phoenix and install them yourself. We did this over a few days on our 2012 2551 and couldn't be more pleased with the results.
We had driven to a local upholstery shop to get an estimate about a leather/vinyl job, and we were quoted something like $4000 for all vinyl (which he preferred) with another $2000 or so for an upgrade to leather on the usual surfaces that contact skin. Some time earlier I had spoken with Carol at Phoenix about what they offered for seat covers, and when I told the upholsterer about the significantly lower price for ready made covers, he seemed skeptical. He said he would be willing to install the ready-made covers for something under $2K, however.
This all seemed pretty high to us, so we contacted Carol again for specifics and got samples of the two recommended (beige) colors. We were quoted $1500 plus shipping for both seats and the recliners. Four weeks later we had a very nice set of leather/vinyl covers made by the same shop that made the original seats, and in the end they all fit perfectly, with only one significant but welcome difference*. The stitching patterns of all of the seats were somewhat different from the originals and to my eye have a somewhat more modern style, but it seems that they still use the same patterns for cutting all the parts, because the sizes and mounting flaps are identical.
The seats and the recliners were pulled out of the RV and taken into the basement. All that we had to do was document the removal of the original covers and write notes on the inside of the fabric flaps as the originals were removed by cutting off the original hog rings. Just to be safe we only stripped and covered one seat at a time, keeping the other intact for reference.
Installing the new covers is accomplished by pulling the hemmed edges or corner flaps of the covers while crimping hog rings around the steel seat frames. I think only the backs of the recliner foot rests required a few staples. There were a few times where we had to refer to disassembly photos to get the attachment ears of the covers pulled and anchored in the correct sequence, but we finished the job in two easy days, and it looks beautiful.
Along with the seats we also ordered a few yards of matching vinyl in case we decided to cover all of the interior vinyl trims in the same color, but they are still holding up and we actually prefer the contrast of the darker beige trims to the lighter more modern seat color.
*The one design change that was made was with the backs of the recliners. On the recliner backs they changed the positioning order of the two padding pillows that insert into zippered compartments sewn into the covers from inside. The original covers had a fatter pillow on top with the thinner pillow in the lumbar area, and the new covers have the compartments reversed, with the fatter pillow filling the lumbar region. It looks better and is more comfortable to sit on.
This turned out to be a very happy resolution to something that had be bothering us for some time. When we bought the RV (used) two years earlier there was no trace of a seat problem, and they just disintegrated after we bought it. Covering the seats yourself is probably not for everybody, but I can attest to the material quality, fit, and price of the replacement covers.