Timberman, I don't know what your budget allows (ie "Big Boys" speakers) but I understand your frustration over the prospect of spending a lot of money (even if willing and able) only to be underwhelmed with the result.
So let me offer what many might consider a novel (offbeat?) idea:
At this point in your search, just forget about making a selection, and instead concentrate on (re)searching out listening venues. It's an obvious, but not often enough mentioned fact that they can't come to you!
It's going to cost you a few airline tickets, possibly, or some long drives (where do you live, anyway?) but in the end, you will make a decision you know is right because it is based on first hand experience.
I'd set up my research effort something like this:
1.) First, I'd contact those who could help me compile a list of (what in they're opinions would be) appropriate speakers for my space. You've started to do that here in this thread. Here are some other ideas: What about talking with Richard Bird at Rivas Audio. Describe your space and get his speaker wish list. Email specific Agonners whose systems seem to reside in large spaces and ask them their impressions/pros/cons.
2.) Once you have say a dozen models/brands, representing a variety of design approaches, stats, horns, multi boxes, line source (Pipe Dreams, Dynaudio, Alon etc) planars (Maggies) call every one of those manufacturers (NOT THEIR DEALERS -- you're interested in doing the evaluating, not having someone else evaluate you!) and tell them where you live, describe your space, and ask them to recommend a place to listen to their product in an environment that most closely matches your own. Explain that while a dealer with a huge listening room would be OK, that if they wouldn't mind, you'd really appreciate it if they would be kind enough to contact customers whom they know have listening spaces like yours, and find out if they would mind demonstrating their systems to you (I can't imagine who but the most paranoid curmudgeon wouldn't be delighted -- you'd just have to go to them of course.) Every manufacture of "Big Boys" (and even small boys) from Wilson to Soundlabs to Alon to Focal to Avalon to Kharma, knows where there favorite children are living and would be delighted to try connecting you, if you're willing to make the trip.
Do it that way. You'll have a lot of fun, meet a lot of great people, maybe see a bit more of America, but more important, you'll come to make an educated decision that will return real enjoyment the first time out.
