Well, you've gotten plenty of great suggestions as to kilts, so my suggestion would be to make sure and stop off in Franklin NC and visit the Scottish Tartans Museum! Franklin tends to be full of thru-hikers and is a very friendly town. Also, there's a new outdoors store next to the museum that's pretty good too!

...and for what it's worth, I'd side with those that suggest wool. One of its strong suits, besides its warmth and breathability, is that it doesn't tend to hold smells and has natural anti-microbial properties.