I'm thinking specifically for this question of the Selkie, however this could apply to werewolves or another similar creature which spends its time both in human(oid) and animal form.
For those unfamiliar with the Selkie myth:
Selkies are said to live as seals in the sea but shed their skin to become human on land.
Selkie stories say that the selkie lives and spends most of its time in the water, as a seal, but clearly has the intelligence and mind of a human, as in the stories they are capable of human speech, they fall in love, and wed human males and females, and bear human children. As with the werewolf, when they are human, they are just like us, and are capable of whatever thoughts and processes humans are capable of.
Seals are somewhat human in their social arrangements, they live in family groups. They hunt both cooperatively and solitary. While the male-dominated species and the harems are not common practice in human society, they are still in our culture to some extent. They care for their young much as we do, and generally their behavior is similar to ours if a bit more simplistic, since we are all mammals and some basics are the same across the board. (I'm not looking at any specific species of seal for this question, by the way, I don't think it is necessary to, but I can choose one if it helps someone with an answer).
Edit: To clarify, along the same vein, seal society and human society are very clearly different. Would selkies understand that aggression between males is not beneficial to their society as a whole, or that killing the young of other males is morally wrong. An ability to analytically and rationally reason out such issues as food shortages, hunting changes, changes to environment (melting ice floes and global warming) and come up with creative solutions will also put a selkie apart from an ordinary seal pack. Would a selkie accept these parts of themselves and incorporate them, or would they eschew the rational and logical human thought process for a more instinctive, natural one?
So if we were to peer into a Selkie society, to take a closer look at a family group or, for example, bring them on land to form a village or town, would it look like a human village or town? Do they cling to their seal behavior, because it is animal instinct, or do they form a more complex and intelligent society using their human minds?
To narrow down the contents of your answers, I'm not looking for a full description of every aspect of a potential Selkie society. Rather, I'm looking for an answer to the basic question of human or seal?
Bonus points for what the benefit is to their society for choosing one over the other.