Hi, I assume the three main Russian tour companies that you've looked at are; DenRus, Red October and Alla Tour. If you look at the website for Alla Tour - www.alla-tour.com and go to the message board, you will find that there is already a message from someone travelling on Constellation in May. They are looking for others to make up a group. I can recommend the evening excursion and concert at the Hermitage, it's opened especially for a selected few and you avoid the massive daytime crowds. Good luck - Jan .
We did a two day tour with Alla-Tour last September. There was no need to make up a party prior to the tour - we just booked for the two of us and Alla allocated us to a group of approximately 12 people on the first morning. This worked very well with a mixture of nationalities - American, Canadian, Brazilian and we thoroughly enjoyed their company.