May be I can be of a little help in RE to St. Petersburg.
The good news is that you have your own folding WC. The bad news, STP, Russia and the rest of Europe are NOT wheelchair - friendly.
It would be more expensive, but your best bet is to go with Star Princess Tours. Several reasons: you will not need a visa, if it is a ship sponsored tour, it would be an Engl. speaking guide (almost 95% signage -all in Russian only!). Then the tour choice - according to your capability, there are museums, palaces and churches that are accesible and this you have to clear with the desk of "Adventures Ashore" aboard ship , a few days prior to the tour. Lastly, your security, the pier is very far from the city center and you are really not having two full days ashore. It will be guide's responsibility to plan to take you to places that are fairly accessible and that nothing bad happens to you, as well as to bring you back anboard on time the next day.
If you wish, you can find my HP report, just down this forum. Dated 12.09.04, with
the title "HP Access in Russia."
My wife is an amputee and for a long time we were planning to take the same
No. Europe cruise, including STP. Then she became legally blind (macular degeneration) and so she insisted that I travel to Ru by myself. This I did last Sept.
and there- the modest knowledge of Moscow and St Petersburg. One advantage I had,
I speak, read and write Ru fluently and with a visa I did not use guides.
If you have any questions, do not hesitate to ask.
Oh yes, about the ballet. I did not go to a theater in STP, but I did enjoy an Opera in Moscow, Bolshoy Theatre. I did not notice, but I am reasonably sure they have elevators, but then to get to your loge and seat - a lots and lots of steps!