Deadliest of the Species was awesome, though it does wander a bit toward the end. Everytime I read it, I understand a little bit more of what's going on. I don't think it make a good novel though, due to it's length. Then again, with its length, they wouldn't have to add anything else in...
The same goes for the Labyrinth novel/series, though neither really ends up telling you exactly what's going on.
After Xenogenesis, I kinda fell off the Aliens/Predators bandwagon for a while, but Destroying Angels would be badass in book form, I've no doubt.