Thanks for your kind words above! I appreciate your taking the time to post them. You really made my day!
Should the time arrive that you embark on that quest for your last pair of speakers, you'll run into a sobering reality - even at price ranges as high as 30 grand ballpark, you'll still have to make tradeoffs! The thing to do is figure out what qualities matter the most to you, and what you're willing to trade off to get them. As far as I know there is no speaker that really "does it all", but some speakers to some things extremely well.
As far as your present room size goes, several of the speakers mentioned would work well in your room, assuming you could position them properly. I know the big Maggies and Sound Labs would work well in that size room, and more than likely the Audio Artistry Beethovens would as well. Note that these all use dipole bass loading, which significantly minimizes the room's influence on the bottom end. Disclaimer - I peddle Sound Labs.
There are probably four general types of loudspeakers one might consider: High efficiency systems; full-range dipole systems; omnidirectional or polydirectional systems; and conventional systems. Each has its advantages and disadvantages, and would be worth experiencing if you haven't already done so.
Best wishes to you.