I looked and looked at your post, and couldnt find some specifics that I feel make a difference.
First... NO TO Paradigm's... look at other threads here to find out why... Also, I dont like the sound, but thats my personal opinion
Are these speakers for music only? If not then...
do you want a 5.1 system, does your budget include that of a receiver and or amp, and what is the primary usage for this system (music or HT)?
For your music selection, I MUST recommend the Thiels. I sold my CS.5's to pay for my B&W 600 series, and though the 600 is an amazing speaker that performs well on a much larger scale of music assortment, I regret selling them. Your specific choice of music preference will make you very happy with the Thiels.
If you want to go to HT, for around 5000 you would meet my next recommendation. Since your space is SO large I would highly recommend you step up and go with a 7.1 system. I have yet to recommend this to anyone in any thread, however I must admit that you have some very specific needs that demands a higher level of spread.
Therefore here is my suggestion for NEW speakers
First you want a pair of
604's at $1800 (new)
a single LCR $600 (new)
2 pairs 602.5's $500 (new) maybe $550, but check compare it with the 602's ($100 less then the .5's) for some people prefer the sound and many prefer bookshelf’s for surrounds
It would be wise to bring home a set of CDS6’s for your home auditon.
Subwoofer, you must ask someone else... I’m not impressed with mine, its a B&W... Marantz 7XXX series (they are releasing a new version very soon with some amazing features)
If you go USED, then I would push you to find a good Thiel Surround Sound System. However Power itself for these systems could suck out a good portion of your cash.
Total $3400 + Sub + Receiver... Will breach the $5000 but not by much.
You may also look for B&W's used, they sell for around 2/3 the original price, and are supported by B&W.
As far as Space is concerned, if you need more oomph, I would up my Rears to 603's. These speakers are amazingly powerful, and are really impressive in large open spaces (I am running a 5.1 setup in a 5000 sq foot space using 2 pairs of 603's, a Marantz 7300 a LCR600 and a ASW 650)