The Empires

plucky, relatively friendly to nature, minimal use of pure Aether, pro-science and art, obvious choice, cliche, etc
pious and holy, believes Aether is the Divine, restricts its use as appropriate, socially strict, big army, a little backward, faith of the masses empowers soldiers on the battlefield, enemy of the Nether
socialist, collectivist, fatalist, higher percentage of sylvan/elementals integrated into core, overthrew previous lords recently, too much Nether in their lands to be too strict about it
association of city-states, random imperial conquests (roman republic pattern: conquest as a means of accruing personal power and paying troops), little national unity, democratic/republican but highly variable from city to city, once was far ahead in terms of civil accomplishment but is falling behind, looks to the past, rests on their laurels
former horse-lords, dekaarian ish, tribal council..
government by stock ownership, richest individuals/companies control everything

http://arcana.wikidot.com/random-nations

Government

Regardless of their level of democratization, all Empires have a noble caste, and a strong sense of chivalry. In particular, they believe:

Those making the laws should execute them
Those declaring wars should fight in them
Those with power and privelege should have responsibilities to match

In its most practical form, this means that the military leadership of the Empires is comprised of its nobles. As technology has improved, the value of an individual human has been comparatively reduced--that is, until the advent of Pure Aether.

There exist treatments using copious amounts of Pure Aether that can enhance any being. Human nobles use the substance to become stronger, more robust, sharper of mind, etc. There are even those who use it to gain supernatural powers, although not every culture is on board with that. Pure Aether supposedly brings out the "true essence" of any being--thus, in order to get fireballs or whatever, these "dirty" nobles must be using degenerate Aether, no different than Sylvans or Elementals. Eww.

Take Two

Another approach, proven to work in several media: Great Houses.

Feudalism and Chivalry survived the democratic revolution: monarchy did not. Noble familes own the vast majority of land--freeholders exist, but are a minority, and are usually muscled away from particularly valuable holdings. Cities are largely independent, seen more as a place between holdings than holdings themselves.

During the late agrarian age, the system had nearly collapsed. Much like pre-revolutionary France, the nobles had chewed away at the rights and wealth of the commoners, while providing less and less value themselves. Small revolutions popped up, while a mass uprising seemed inevitable. Instead, there came a compromise: with the industrialization of Aether, land became more valuable than ever, and control over cities and towns, and even lucrative trade taxes, seemed a paltry thing to spill blood over.

As in our world, the rich figured out that capitalism was even better than feudalism--all of the rewards, none of the risks. As such, over a couple centuries, most actual revenue-generating operations were privatized. The nobles turned into a lending class: investing in companies and even individuals who would return dividends--or not at all. Thus, they retain the lion's and the lioness' share of wealth, while doing almost none of the work.

Almost none, that is, because they are still expected to take the field in combat. After all, wars are fought over land, and they own all the land--thus, wars are almost entirely between noble familes.

The Old Guard

Nations stuck in an older era, outclassed by the Empires, but not important enough to conquer (just yet)

Tribal Lands

The rest of the world, more or less conquered by the "civilized" empires, but not nearly to the extent in our world. Think if Indian Reservations were more populous, numerous, and powerful, and the treaties were actually honored somewhat, though conflicts abound.