The CiviliansThe little people. The ones most frequently in danger during villains' onslaught, the one who become a statistic during the alien invasions, the ones heroes swear to protect. The most important factor in civilian population is how they feel about Superhumans. As noted in part 1, The Team is the most well-known and well-liked team on the globe (or a big part of the globe). But if the general populace detests Superhumans and sees them as walking WMDs, that's analogous to saying that The Team is the least hated example of Superhumans and still are constantly trying to prove themselves. There's a couple of viewpoints that can crop up regarding Supers:
-Fear/Hatred: Supers are inherently dangerous; they cause damage to cities when they fight. Also, Supers are causing aliens/demons/whatevers to attack Earth...if the Supers leave, Earth will be unmolested as it was before the Supers emerged (of course there usually have been invasions prior to the emergence of Supers, they've just been forgotten/mythologized)
-Cynical: Yeah, the really powerful Supers are good guys but one day some crazy asshole will win the superpower lottery and turn Earth into a hellhole.
-Optimistic: The inverse of the above, it's only prevalent in areas ruled by villains or Supers with extremely loose morality.
-Idealistic: The good that Supers do far outweighs the evil. And we can trust them because (most) are still ordinary people deep down.
A "realistic" setting would have a mix of Idealistic, Cynical, Fear/Hatred, and simple indifference about equally distributed. Marvel leans toward Cynical & Fear/Hatred viewpoints. DC leans toward Idealistic viewpoints.
PlacesSo now that I've ranted about civvies, let's focus on locations.
The Villain-ruled CountryThis smallish, fictional country is ruled by a villain or an extremely pragmatic hero who took control after ousting a "corrupt" government. This country is usually in an are with a recent history of war and instability such as the Balkans, Eastern Europe, or the Near East. The ruler might be a total despot or a "tough but fair" figure: Population viewpoints are split between Idealistic, Fear/Hatred, and Optimistic (if the ruler is a jerkass), but any viewpoint that challenges or condemns the ruler is unlikely to be expressed publicly for fear of retribution.
Oddly, the regional impact of this country seems to be frequently neglected.
Examples in comics: Latveria (ruled by Doctor Doom); Kahndaq (ruled by Black Adam)
The Hero-ruled CountryRuled by a Hero, this country is a hereditary monarchy. You'd think this country would come into conflict with the above but it's usually placed in a different region than the above. It also has a surprisingly low impact on regional politics. The majority population viewpoint is Idealistic.
Examples in comics: Wakanda (ruled by Black Panther); Markovia (ruled by Geo-force)
AtlantisAs something that has intrigued Humanity for centuries, it's no surprise that Atlantis gets heavily used. The exact nature of the Atlanteans varies but they generally have superhuman durability (to withstand pressure) and strength. They can breathe underwater but being capable of air-breathing could be a rare atavism/mutation. Atlanteans tend to be lead by a ruler that is half-Human/half-Atlantean. Depending on how scientifically accurate you want to be regarding interspecies breeding, this would mean that the Atlanteans were once Human.
The Lost WorldWhether it's an unreachable island or a secret spot under the Earth, the Lost World is a place were dinosaurs, cavemen, wizards, and Conan rip-offs dwell. There are also occasional bits of ancient hyper-technology that boggle the mind. The Lost World is a savage, tribal land where hunting-gathering is the main mode of subsistence. But feel free to insert random castles and a suitable agrarian support network for them. There's also plenty of room for Lovecraftian elements.
Now, let's head into space and the outer reaches of the galaxy!
Or you can explore parallel Earths if that interests you more.