Whew. A lot of advice here but I can't help myself.
1. I have a pair of Thiel CS6 and they do everything you want. I live in central Washington and if you are in the area you are welcome to come hear them. You are way ahead of the average user in that you understand that Thiels are hard to drive. I'm using a Krell KSA 300S which is one of the amps that Jim Thiel used to voice them. I run mine full range with a Velodyne subwoofer covering the bottom octave.
2. If possible I recommend that you attend an audio show so you can get a feel for what is out there. It's much easier to buy used stuff if you have a better idea of the range of options. I have been to three shows and have found that my system holds up to pretty much anything under six figures.
3. One option that I don't think has been mentioned is the Revel Salon2. These are some of the best sounding speakers ever made and they come up frequently on the used market for $10 to $15k. You can't go wrong with a pair of these. They are somewhat easier to drive than the large Thiels but still need a robust amp that will increase its power into low impedances.
4. For a research exercise it would be very helpful to review Stereophile's Recommended Components over the last 25 years or so and see what speakers were rated as Class A. IMO the state of the art has not changed that much for speakers that cost under $100k. A top rated speaker of 20 years ago still sounds great today. That will give you a basis to sort the wheat from the chaff if you are looking for high end used speakers.