R2G was, by far, the best option. I know that the sofa is "cheap" compared to what a "quality" couch would cost. (I paid $3200 for a three piece sectiona.) However, going into the showroom, having oodles of oodles of styles we could sit on, and giving the salesperson my card and having them take care of literally everything else (down to installation and placement) was amazing. The couch also looks great and is comfortable as hell.
The thrift shop couch was the second-best experience. Terrible selection, but we got lucky in finding a couch we liked. As it happens, the couch was an Ashley Furniture couch, which is kind of like R2G. We had to move it in ourselves, which was extremely annoying. But it is still standing and is still a great couch. (It's my office couch now!)
The IKEA couch was by far the worst. Buying the couch was easy, of course. Putting it together sucked, but whatever. The quality of the couch, though, was a disaster. Super lumpy seats within months of use, color stains discolored the couch permanently, even after cleaning, looseness, etc. I wouldn't buy couches from them again.
That said, we have tables from them that are still great. So maybe IKEA for small furniture you don't care about is the move.
Granted, it's just six months old so I don't know yet how it'll hold up. But I'm very happy this far.
I attribute this to much of California only becoming as densely populated as it is (which is to say, not) after around the 1950s. While there are families who have lived here for five or more generations, they’re by far the exception rather than the norm. The overwhelming majority of people who are here have comparatively shallow roots, didn’t bring furniture with them when they came here, and even if they have access to good furniture from elsewhere, it’s cheap and good enough to go to ikea.
Though and I say this anecdotally, when I moved back to the States I ended up refurnishing most of my house using street finds. We're talking like 10 different furniture finds include a futon frame (we bought a new mattress). Only 1 of those was upolsteres but was in great condition.
No bed bugs, I got lucky.
Edit/addendum: The bed-bug-sniffing-dog, while a very good boy, is a total scam.