Thanks to everyone who replied to my post. As it turns out, this story has a happy ending...
I read Gary's post this morning, and I started thinking that he was right--it really was a bummer that this guitar hadn't had the tone I was looking for. But then again, Twang Gang was right in that there was something I liked about the tone when I first heard the guitar or I wouldn't have bought it. When I first played the guitar at my local GC, we set things up for distortion, and it was this really ragged-edged, nasty, mean kind of sound that I really liked. I mean, my other guitars will do that kind of thick, smooth distortion that is good for some things but isn't really snarly. But the Gibson distortion was major in-your-face snarl that didn't compress and disappear into the back of the amp. It was striking, and that's why I bought the guitar.
When I got the guitar home, though, I couldn't reproduce that tone. I tried it though both of my main amps ('82 Fender Concert and Marshall 2525C), and I just could not get that snarl. So, I figured that what I'd heard at the store was largely the effect of having been able to play the guitar pretty loud at GC (through a Fender Deville) and having played it right after playing for a while on an Ibanez with flatwounds on it. So, given that there were a few other issues with the Gibson, I had decided not to keep it.
But I'd gone back and forth about this guitar for a week, and even though I had decided to return it, there was still a part of me that didn't want to give up on it. Yeah, it has its issues, but they can all be dealt with at some point since none of them really affect the the guitar's playability. So, I was thinking about the only two Gibsons I've ever played, and I realized that not only had I played them both at GC but also that in both cases, the same sales guy had dialed in the distortion. I never really thought to pay that much attention to what he was doing. So this morning, I just called the guy up and asked him how the heck he had set those amps up. He gave me his formula, I got out the Marshall and set it up, tweaked it a little, and voila! There was the tone that I bought the guitar for. There was that snarl.
So, a few years ago, I picked up a Fender California Series Strat that I put Vintage '62 pickups into and strung up with Blue Steels, and it has one of the best clean sounds I've ever heard. Lots of airy chime. I've never done much with distortion until recently, though, but I'm glad I finally got it figured out and am happy that I decided to work with the Gibson a little more. Needless to say, I'm keeping it. Now I have a Fender that plays like butter and sounds like heaven and a Gibson that plays like butter and sounds like hell. I love it.
Thanks to everyone for their replies. I appreciate it.