the big one: how do you choose speakers? By what features, data?

@ct10 If one has $8900, yes :)

I think there is a lot of great value around 3 and 7K  

If cost is a constraint, i would go with the competence level of the speaker engineer. It takes very competent engineering to offer something good at affordable prices. On the other hand, it is much easier to make expensive speakers that sound good. The latter doesn't take too much genius.

On that note, Andrew Jones (Elac, Mofi) Danny Richie (GR Research),  etc are names that come to mind. Lately, very reputable brands with serious engineering aptitude like Yamaha, Technics, etc are releasing hifi speakers at relatively affordable prices, i.e.,  under the 10k price bracket at least. I would go with those. 

If cost is no object, TAD, high end JBL, etc come to mind.

Andrew Jones Was with TAD before Elac. Perhaps best speaker engineer.  

decide on budget, shop used, read reviews, consider measurements. One of the most neglected things is matching the speaker size to room size.

There are multiple great speaker engineers out there. It would be wise to follow all of them for their pearls of wisdom.

Raymond Cooke- KEF- taught most everyone how to design speakers and almost every one that followed him looked up to him as a leader. He worked for Wharfedale and left to pursue "the science" of loudspeakers (not "the business") . He is credited with a focus on research and scientific principles and has many inventions to his name. He spurred many other careers, such as development of the BBC monitor kit (LS3/5a) that spurred several BBC engineers to open their own manufacturing operations to build this monitor for the BBC under license (Spendor, Harbeth, etc). Raymond sold the company in 1992 to Gold Peak, a Hong Kong based company that owns many other brands. Suprisingly, 1992 was when the KEF driver kit for the LS3-5A was finally discontinued.

Doug Button. He is now with Sonos and did the ERA 300 but also was with EV (Vented drivers) and then JBL (EON) and developed industry changing products at all of them. He is amazing.

Billy Woodman-ATC- developed some of the lowest distortion drivers ever built, developed the mid dome idea and pioneered active systems (impacted the high end pro market).

ilpo Martikainen- Genelec- on a parallel track to Billy and developed active monitors, the first quantity manufactured professional active monitor system. He impacted the worldwide pro market significantly and spurred many copies as "active" became the way to do it.

There are many many more......