This is a draft.
Amber's Melting Pot
Amber society is exceedingly cosmopolitan, as befits the crossroads of all worlds, the place of which all places are but shadow. Amber only has one major population center — Amber City — and it is where all things of significance happen, although there are noble estates out in the country, many associated with small villages.
For all of its cosmopolitan nature, Amber is also, in a way, highly provincial. What happens in Amber really matters; what happens in the Golden Circle matters a fair amount (and matters a whole lot if it has implications for Amber); everything else isn't of much interest. The ordinary Amber citizen is aware that Amber is the crossroads for what he thinks of as "other worlds" (although the term "shadow" is known and sometimes used). But most of those other worlds don't have much daily relevance for him, and so they exist on the periphery of his awareness, at best. (This is sort of the equivalent of the New Yorker who doesn't really care about anything that's not affecting New York City.)
Although social classes live apart from one another, and to some extent the natives live apart from the foreigners, the city is a large melting pot. Interaction across social classes and place of origin is commonplace, although there are certain forms of social snobbery or nationalism that are still prevalent amongst some. Wealth can overcome birth, although money is considered transient, while blood is blood.
The royal palace is at the center of court life. It is the social center for the upper classes, whether the nobility or upper-crust merchants, and to some degree, for those who serve them. It is not merely a place where the royals live; it is the working center of government and the main arena for upper-class life. For everyone else, the primary point of potential mingling is Amber's main marketplace (Main Concourse and Market Street).
Long Life, and What to Do With It
Everyone native to Amber (or indeed, to most of the Golden Circle) is long-lived, and the more important and significant someone is, the likelier they are to live a long life. However, correspondingly, the birth rate is low — the longer-lived a family is, the lower its birth rate tends to be. Consequently, in Amber, every birth and every life is precious, and all the more so among the upper classes. Moreover, one can afford to take the long view on things. However, people hatch plenty of short-term plans, and struggle for short-term advantages; they regard failure as just a temporary setback, knowing that they will live to try again another day.
To some degree, the game of politics is played for score. In a long life, one must do something for entertainment, and beyond chasing the latest fads, finding and contesting worthy opponents is the way one passes the time, at least in high society. This finds expression in a variety of ways — in trade, in family alliances and rivalries, in a variety of schemes to control particular things. In the seven or so years that Oberon has been missing, these conflicts have grown in scope and intensity, since the throne is a genuine prize, and with the change in who is in power, there is a general reshuffling of the social order of things.
Importantly, however, those of Amber are notably reluctant to escalate matters to the level of mortal conflict. In a long life, one can try again if one loses, but if one is dead, everything is rather permanently ended. Most people fear that if they escalate a conflict to that point, it will set off a chain reaction that will leave a lot more people dead. Murder, whether accidental or deliberate, is an extremely serious thing, and although there are duels, care is usually taken to ensure they are not likely to be fatal ones. Consequently, creative forms of revenge, usually going after the things that are important to the person rather than the person himself, are something of an art form in Amber society.
War is treated differently from personal conflict. Despite the risks, Amber is often involved in military engagements of one form or another. Mortal peril is part of war, and courage and sacrifice are still virtues. Still, historically, Oberon was reluctant to spend the lives of his own citizens in warfare; nonetheless, he sent his own children to command armies drawn from shadow, and certainly did not shy from using his nobles and Amber's professional officer corps for the same. And given the nature of warfare, some such valuable lives are sometimes spent in battle.
Amber's standing army is quite limited, but its navy is significant, as is its merchant marine. Nearly every Amberite male has spent some time at sea. Most citizens are capable of fighting if called upon. It takes considerable time to raise and train an army in shadow, and consequently, to a significant extent, Amber is dependent upon the protection afforded by the shadows of the Golden Circle, and by the shadows of Arden, which is the easiest entry point to Amber other than the sea.