The JL Audio W7 12 or 13 is an awesome driver. see link
I am on the same plate - want to have some fun following the DIY approach, I am done with the furniture (built it myself) for my sanctuary, now time for speaker cabinets. I don't have recommendations, sorry, but I was thinking along these lines - if I pull some $200K speaker and see what drivers (if not proprietary) they use - would that be a good enough indication? Myself I was looking at Lambda Series TD12H (http://aespeakers.com/drivers.php?driver_id=6) or SS Iris OB @ http://www.hawthorneaudio.us/catalogs/index.php?main_page=product_info&cPath=3&products_id=4
Would be very interested to know what you come up with, cheers!