I would say China other than Beijing and Shanghai.
But even in big cities there are parts where people don't even understand "yes" or "no" Also, recently I had some troubles in Spain as well.
So, I guess if you can also learn Chinese and Spanish then you could be anywhere in the world.
travel.stackexchange.com/users/4022/toy
For example South America.
In my experience, English knowledge was generally poor.
You would need to know at least basic Spanish.
It would be easier to say, where English and Russian would be enough.
I expect, that Russian would be useful only in former USSR and maybe some Eastern European countries.
In Western Europe should be relatively easy to find someone who speaks English.
Then there are all English-speaking countries and their former colonies.
My bet is that anywhere else, than I mentioned above, only those two languages might not be enough.
travel.stackexchange.com/users/2513/Tschareck
In the central and western Africa.
People beside of their own African languages know French and Arabic in most African countries but they do not know English or Russian.
Small cities or rural areas of most countries around the world that they do not speak English or Russian and only know their own mother tongue.
You can find them from India, Turkey, Iran and China to South America even in Europe in France, Italy, Germany or Spain!
I think more than Russian it is better to learn Spanish and French.
Nowadays knowing Mandarin can help a lot too!
travel.stackexchange.com/users/4381/Persian Cat
The former satellite states of USSR.
While old people still speak Russian there due to enforced "friendship" with the USSR, many people are now much more hostile because of the tainted past of oppression.
While driving in the rural parts of Poland, I needed extensively my word list of polish phrases.
Forget English and Russian there, I was even more successful with native German.
Young people in the cities are eager to learn English (searching jobs in Western Europe), but in the more remote parts Polish is the only option.
I suspect it is the same in Czech Rep. and Hungary, it would be fine if someone can confirm this.
travel.stackexchange.com/users/7442/Thorsten S.
It'd be easier to just say where you can get by.
List of English speaking countries in order of % of English speakers .
A similar list for Russian .
Serbian and Polish and Ukrainian are very close to Russian so replace the Russian in the previous link with Polish and Serbian and Ukrainian.
travel.stackexchange.com/users/4735/David
I speak Russian and English. Will those 2 languages be sufficient to travel anywhere in the world as a tourist? Or there are some regions where it wouldn't be enough?  By sufficient, I mean, I would be able to buy tickets, book a room in hotel, order taxi, use a restaurant etc.
Where in the world knowing Russian and English will not be enough?
travel.stackexchange.com
<language-barrier><russian-language>
travel.stackexchange.com/questions/14144
travel.stackexchange.com/users/4731/Anixx
Travellers to small cities or rural areas of most non-English speaking countries around the world, especially in China, central and western Africa and even European countries like Poland may need to speak the local language or a common language like French, Arabic or Spanish. In many parts of the world people only speak their native language, China is a good example. In West and Central Africa, Arabic and French may be spoken but English and Russian are unlikely. The best languages to learn may be Mandarin, French and Spanish.
In most parts of China people do not speak Russian or English. In Central and West Africa, people may speak Arabic and French but not Russian or English. Many people in rural areas everywhere only speak their own language. In rural Poland people only speak Polish. French, Spanish and Mandarin may be the best languages to learn.