LuxuryRogue, thank you for your comments.

I have decided to go with Avantour to make trip arrangements. The company has been recommended by several FTers. There are several luxury tour companies who advertise much the same travel in Uzbekistan and Turkmenistan but at sharply higher prices. It's not obvious to me that the additional cost results in additional comfort. They can't create luxury hotel stays when none seem to exist. One company noted this:

"Cox & Kings uses the best available accommodation in Uzbekistan. However, outside Tashkent the standard is relatively basic. This tour involves some long drives and walking over rough terrain."

Thus, I have asked for pricing for suites wherever possible, as well as the upcharge for the train. I'm thinking this is like early travel to China when accommodations were very basic. It also appears that border crossings are done on foot and require perhaps 1.5km of walking. It's fortunate that we have learned to pack lightly.

This trip needs to be arranged at least a couple months in advance as visas are required for each country. We have to provide a lot of information and then Avantour submits the request. Turkmenistan requires the visa request no more than 3 months in advance and at least one month in advance. Visa processing takes 5 to 20 days. The visa can be picked up on arrival. For Uzbekistan, Avantour sends the visa request to the Ministry of Foreign Affairs in Tashkent. Approved visa support is telexed to the Uzbekistan embassy in the US. I then need need to submit our passports to get the visa.