Thank You. I still can't believe we went.
If you do go, St. Petersburg is the place (although Siberia intrigues me).
However, I've not heard anything good about visiting Moscow. Another European group we ran across in St. P. said it was a very dirty city. (Industrial?)
I have been to Moscow many times. I would not characterize is as a dirty city, rather as a thriving metropolis, with somewhere around 18 to 22 million. Seeing the Kremilin, GUMS and the Metro is worth the trip.