Fat down toward the fire, brisket whole time, but fat cap side of butts down at least 2/3rds of the cook. I haven't always done it, but flipping them once or twice is probably a good thing. Otherwise, fat down whole time. Even if the fatcap side starts to fall apart, it's a lot more forgiving than the other side and will be slower to dry out. I'll trim the cap a little and/or score it, and usually it crisps up nicely to mix in with the butt, especially if not using water or cooking much under 250. It's the very best bark you'll get if rendered crisp. From now on you can bet I'll be looking at it in the store to make sure it's not too trimmed...just the opposite from if I was planning on foiling.