What do you guys do for underwear? Every layer that I wear is some sort of synthetic except for my underwear. Do you go "commando" or do you just wear your normal undies?

I just wear normal undies. You can buy synthetic undies if you want. Also "wind briefs" that runners and skiers use are worth checking out. They are just synthetic briefs with a wind panel in front.

I use normal undies, but then a layer of synthetics over the top.

I go commando if I am wearing long poly pro underwear. If it is really cold, I go with the poly propylene long johns , then a layer of wool army long johns aand finally my sweedish wool army pants.
okcmco