Need advice on what to look for in a turntable - budget $6K to $10K

I think, any turntable in this price range will sound excellent. You just have to figure out what exactly you are looking for and what cartridge you are going to use. I understand, you plan to buy new table/arm/cartridge. Your reference to compare to should be one of the better two track reel to reel tape decks playing at 15 ips speed. Table set-up closest to it would be your choice. Easier said than done, I realize that. But don't rush it. You also want the turntable to be reliable, easy to operate and maintain and supported by the manufacturer.
But first question is belt drive or not or it depends. 

Rega RP10 with alpheta 2 installed from factory.

Garrard 301/401 or the newer 501 set up with two arms one 12" one 9 or 10" with arms lf your choosing and a high end plinth in the flavor that suites you tastes and you will live music all the more.

Very good questions, mm.

What you get in the better tables is a lower noise floor and a higher level of detail retrieval. Just about anything in your price range will sound very good indeed. To optimize requires some experience, which is rather fun on its own.

There are some subjective and some objective criteria. First, how good does the suspension have to be? My house is built on rock and my table is connected in direct line to the foundation, and there are no highways, rail lines, or other sources of vibration within miles. That means that a suspension is worthless to me - so I didn't pay for one.

Are you very keen on the exactly correct speed, for example, if you have perfect pitch? If so, then make sure that the motor controller has a speed adjustment.

Are you offended by a little quirkiness? For example, my turntable requires me to spin it by hand to start it. Doesn't bother me - I concentrate on the low noise and the saved dollars. Offends others.

Subjectively, what you must decide is the weighting of noise and precision. That is a matter of taste and a matter of experience.

That said, there is one major complication - set up. Few retailers seem to know how to set up a turntable, tonearm, and cartridge, and fewer still will bother. That complicates any comparisons you make.

My suggestion is to listen to a bunch of different systems, preferably amongst your friends. When you find a sound you like, you can take the knowledge to a trusted dealer - and if he's in the next state, the trip will be worth it.

As to brand, I like Nottingham Analogue's Dais. For a tonearm, I like the Trans-Fi air bearing, which is probably the best buy in audio for $1000. For cartridge, I like Koetsu.