i picked these up on some what of a whim. as far as comfort goes, well there is no substitute. i literally feel like im just sitting around in my boxers when i wear these. sizing is generalized much like their shorts. if you are on the slim side stay to the smalls. they are REALLY roomy, but the lightweight feel more than makes up for extra material.
bottom line: want to feel like you could just lay in a hammock all day drinking tea (or brews), get 'em, wear 'em, love 'em.