^ Remember when people made one word posts? Those were the days... Now it's just... two consonant posts.
Anyway, what i like to think about the Alien... I like to think that the xenomorph is a highly intelligent artificial creature, flawed in its high intelligence, because even though its purpose is to spread and consume, it is more efficient alone than in groups. I like to think of it as something very big that can fit in the smallest places. A black horror that you just can't find; but you know that it's constantly watching you, waiting for the moment when you are the most vulnerable. It knows what you will want to do in that situation and it knows how you would do it. And it knows how to take all that away from you, so that there's nothing left to do and you are paralized, waiting to die. Also, they like to nap when the only survivor of the Nostromo is about to kill them.
About the Predators, i like to think of them as a society based on mutual respect and discipline, who train to become the greatest warriors that they can be. Honourable warriors, that is. And then they hunt around the universe for challanges. Even if they don't hunt for honour, but for experience and testing themselves, they are honourable because they are tought to be so.