Greetings! I'll visit both cities in December and am checking on shops to visit in both places. I've already asked in a couple of other groups so I'd expect that I could write a one-page post that covers the subject in more detail than I'll hear back but I wanted to check anyway. If there's interest I'll write about what I've learned, or what I experience in visiting.
Per the general background I've ran across tea is popular in Russia but Russian tea isn't necessarily common there. Russia doesn't make all that much tea, only a little in the Sochi area. A tea blogger friend reviewed a few Russian-produced teas and they sound ok but reading between the lines it seems like most of what is being produced is pretty far behind related to Chinese tea standards. The better exceptions to that still might be really interesting. The Russian tea tradition is really based on Chinese and Indian teas, again per my understanding, with some overlap with the Turkish style of preparation, related to making tea very strong based on a long brewing time and then diluting it. Others have mentioned that tea mixed with jam isn't unheard of.
About me, I write a tea blog based out of Bangkok, Thailand (Tea in the Ancient World), but I'm from the US. I suppose I'm really more excited about actually seeing Russia and soaking up just a little Russian culture, to the extent that works on a short vacation, but there isn't much to discuss about that.