Loire Lover -
May I first ask whether your trip is some sort of an organized tour, or if you are doing this entirely on your own? Presumably a tour would provide lodging and a number sightseeing side trips, perhaps even a meal or two.
Please let me know. I can definitely recommend some less-than-obvious places for lunch, dinner and your most important wine-free meal of the day, breakfast. And some places to stay at. Particularly, in St.Petersburg; I will need to refresh my memory regarding Moscow. But it would also be good to know whether you plan to dine with a large group or in a more private setting.
Sightseeing - do you like well planned visits to famous cathedrals and museums, or would you wonder off and explore the city on your own once in a while? You can of course do a bit of both.
Hope I can be of some help.
SK