I think all of the above recommendations are good ones.

Let me add one that's going to sound a little weird: Dry socks, two pair. If you're out slogging around all day in your poncho, you're boots are liable to soak through. If you hunker down in your bivy with wet feet, you're going to be miserable. I typically carry one pair of athletic type socks and one pair of heavy wool socks, just to wear if I do have to hunker down. Of course I typically have a pair of gloves and a hat too, but those are specifically for having to shelter overnight.

HJ