My clunk is fixed!
So, after my previous experience with a dealer being "unable to hear" my clunking noise, I went to another dealership when I got the recall notice for the washer hose recall. I made an appointment for the recall, and told them about the clunk, the missing exhaust heat shield bolt, and the raised trim on the right side steering wheel switches. The dealership proactively ordered sway bar links based on this forum's experiences (that's a nice touch). After doing the recall, replacing the sway bar links, and fixing the other issues, the tech noted that the clunk was still present. He called me to get my take on the problem, and I informed him that I noticed that the clunking went away under light braking. He told me this gave him an idea, and called me back about an hour later to tell me my car was fixed and ready. When I got there, he informed me that I was hearing the brake pads clunking around in the caliper, and that's why when the brakes were applied the sound went away. He applied a shim and applied some brake-quiet lubricant to the back of the pads, and my car sounds like it's new again.
I apologized to him about the incorrect sway bar link guess, and he informed me that it was probably good to swap them out anyway, as he'd done 3 other sets on Sonics. I got the feeling that he wanted new ones in there anyway.
So, kudos to Camp Chevrolet in Spokane for making this right for me. This is a real surprise as the last time I went there for a warranty problem, it took them 2 weeks to get a part. They actually listened to me as a customer, and it was a nice treat not to get treated like an idiot.