Ugh. Getting through those six pages was hell guys. For starters, I want to point something out before I get into real life examples. And that is: Small scale societies tend not to control their populations via fighting and infanticide. The tendency, as I understand it, is they use out-migrations and settle new areas. This makes sense since any amount of serious fighting would leave their small scale economies completely devastated (and cause villages to dissolve). They tend to use relationships, debt, and credit to form exchanges. There's a few exceptions, such as the Yanomami, but even they tend not to be as violent as some author's describe them. *gets off of soap box and returns to topic*
Okay . . . You have several real life models to pull from for polygamy.
There's the Tibetan system, where you have one woman marrying multiple men. Usually brothers and the stated 'reason' (by ethnographers, I believe) is to keep land ownership in the family. So, infrastructure and the environment can have an impact on these types of social relationships, this could help 'inform' world gen (obviously historical contexts of civs are important as well).
On the other hand, you have polygamy where powerful actors tend to marry multiple wives and have concubines *cough* Cao Cao *cough*, but your average Joe only marries one woman.
You have the Canella, where when you marry into a family you are considered the 'husband' of all of her sisters as well (and their husbands are considered your wife's 'husband'). A bit interesting because that seems to radiate out and include all of the cousins (and their husbands) on the mother's side. Then again, I do believe that it is a matrilineal society.
There's also the case of Brazilian travesti, though they might be more polyamorous. They tend to have one boyfriend while having many clients. The material and social exchanges are interesting in that case. If prostitution ever makes it into the game it might be worth taking a look at how real life prostitutes juggle their social and intimate relationships. Quite a few women-men from American Indian traditions tended to be polyamorous as well though you did have monogamous pairings too.
There's also the Bedouins described by Abu-Lilu Lughod. Polygamy is common and the preference is to marry first cousins (first wife is usually a first cousin). This preference is due to the fact that a wife can leave at any time (though she can't take the kids), so first cousins tend to be trusted more. At least, that was my understanding.
Essentially, anything we can imagine plus some in nearly any context arranged in any fashion. Our little dwarves are based on Homo sapiens and we are adaptable as I'll get out.* Hell, there's no reason why you couldn't have 'homosexual' incestuous polygamy as the standard and once every five years there is a wife/husband exchange across families in order for pregnancies to happen. Though, I would recommend a reading of Vincanne Adams et al "Sex and Development" since Adams makes the case that sexuality is a new phenomena and the behaviors, feelings, etc that we proscribe to specific sexualities are not as hardcoded (socially) as we make them out to be. That is, sexuality is a recent phenomena. This seems to be the case in non-Western societies (and this really opens up the sorts of marriage arrangements we can see).
Oh, and I nearly forgot to point this out, matrilineal societies, from what I've read, also tended to be monogamous (the Canella are an exception). I haven't heard of many that were polygamous or polyamorous. The Iroquois, for instance, were matrilineal and monogamous. Most American Indian tribes that are matrilineal that I've read about tended to be monogamous. This isn't to say this is the 'natural' course, just with most of the cases that I'm familiar with, this is the case. Anyone claiming differently please include specific examples. Throwing around assertions with nothing to back them is, well, it is counter-productive d*** it.
*There is even cases of multilingual exogamy (AKA, you can't marry someone who's first language is the same as your own).