Having only watched most of season 1 and a couple of episodes of season 2, I've nevertheless got a theory about the cylons: they had infiltrated human society long before the attacks, with a detailed plan on which humans were to survive and which weren't, with the plan that they would be guided (through various means) to eventually go to Earth. All that's unclear to me is *why* the Cylons would want to have the humans lead them to Earth. So virtually everything we see in the series (first season at least) was premeditated by the Cylons. They've set the events in motion, with a controlled cast of humans, and with only the occasional pull of a string they are sitting back and watching events play out as they'd planned them.

What makes it interesting is that humans are emotional - thus not fully predictable - and what's more, the android Cylons are, too. So it's almost as if, in implementing their plan, they were also introducing the flaws in their plan.