St petersburg? Check out the tours with your ship as I am not disabled but did come across a very nasty incident involving a disabled elderly gent whilst on a tour that included the underground,although we had two guides with us that were russian I had to take full responsibility after he fell on the very fast and deep escalators that involved other passengers.I feel sure that you will be looked after by the ship but please be aware any tour involving travelling on the underground not rec ommened for any people with disabilities especially wheelchair users.iwould think there are ample overland ships tours to enable you to visit st petersburg safely and enjoy. Check with tour manager on board for the most suitable one for yourselves.
I went on Jewel of the Seas and we booked our trips in St Petersburg with a Russian agent. I am sure she could arrang something for you so you could take your electria wheelchair and it could be a lot of walking and hard work for someone to push your folding chair around.
try an email to http://www.alla-tour.com/.
Beware of booking a trip on you own as you will need a visa and these work out very expensive I would get in touch with P & O or go on the website where you will be able to see all the organized tours and book online if you find one suitable. I booked the St Petersbourg coach tour which takes you all around the sites and you can get off the coach if you want to. Their were some disabled people on this tour but most of them stayed on the coach for the whole tour.
Apparently there is a visa exclusion waiver for cruise passengers - as long as your ship stays for less than 3 days, and you don't disemark without your tour guide. After doing some research it looks like I am going to get an independent tour as it will be better for us to travel in a much smaller group.