Guys, I've visited many countries. And I mean like 40 of them, mostly european. Many european cities from huge business centers like London to small swiss towns in between the Alps and beautiful lakes. Obviously Moscow and S-Peterburg also. Now I have an opinion
1. While SPb is one hell of a city with its unique atmosphere... it has some problems also. Wealthy ppl mostly do live outside of SPb, like farther from the center than Newark is from Manhattan. It is true. Another factor is the climate. Much less sunny days than in NJ, and it's colder. So I think it's a non-factor in the equation for Kovalchuk.
2. While you listed DC as 4,7M it doesn't feel like that. My experience was very different from other USA cities. DC feels much more like european town, at least it was for me as a tourist (and should be for a wealthy pro athlete). We had a small trip out of DC to some place in Maryland... and it is beautiful. I sensed a good relaxed vibe from the area. I believe the place where Ovechkin lives is also like what we have seen. Green, warm, convenient and safe.
That is not what you get around Moscow. Hardly even close. So you should not expect OV saying he wants to go home. You will hardly get such a level of comfort in Russia. Yes, his home is Moscow, but he's spending the summer there. It's enough, I would guess.
3. I think one can say NY, London and Moscow are similar cities. Just the different english accent.