I gave up on cotton for sleepwear years ago. I started wearing wicking materials intended for workouts and they actually keep me warmer by drawing moisture away from my skin. With cotton I'd feel all clammy if I would sweat at all. As a bonus most are smooth and stretchy and extremely comfortable.
I'll second the suggestion of Duluth Trading for knickers. Their boxers are the schnizzle. Like going commando without having to go commando. They last for years too.