What writing, specifically?

[MessiahSimple]

After sounding like a bloated ego with a keyboard for so long, I hope it's not ridiculous to discuss this from a point of no knowledge.

What writing examples are most valuable in a portfolio, or to have a working knowledge of before confidently calling yourself a narrative designer?

Script treatments? Dialogue? Extensive overview? Novel-form story?
It's not hard to assume that every one of these is something you should be working with, but in terms of getting noticed - what are your interviewers looking to judge you on? This implies the corollary question of what all narrative designers do, i.e. pure script (playwright-style), dialogue, setting, all of that nonsense, etc.

Also, for the non-pros, what skill sets are you guys all developing? There's a lot of discussion of, "I have talent and passion and whatnot, but nobody has hired me," so I'm curious as to what exactly that process has entailed for you all.