My method sounds very similar if not identical to some of the other methods listed here already. I rub mine with a dry rub the night before and let sit in the fridge in plastic wrap and foil at least 12 hours. Then I smoke them for 6 hour on the horizontal barrell smoker. I have wrapped them in foil as soon as 2-3 hours and as late as 4 hours into the process.
I'm glad I read this thread today as I never realized that the sign to wrap them in foil is that they START to shrink back from the bone. I always judged mine for the wrapping by the exterior condition. My first few attempts turned out charred skins (outside), but increadibly tender and fall off the bones insides....NO BOILING. So I started wrapping them in foil trying to reduce the amount of charring. I have sttled on about 3 hours for the perfect balance. I too spritz with apple juice/cider every hour as well as a good soaking prior to the wrap in foil. I like the idea of adding the bbq sauce with the apple juice/cider prior to foil wrap. As a matter of fact, I'm smoking 2 slabs of backs right now. I'll give the sauce trick a try today. I'm also trying Apple wood chips today instead of hickory...just for something new.
My rib of preference: the backs. Spares are too fatty for my taste...I like meat.