Well, first of all, getting your partner's head inside your foreskin feels pretty damned good. The foreskin has more nerve endings than any other human anatomical structure except for the clitoris, and they register the stretching as well as the pressure to make for a very pleasurable setting. Since the average foreskin only has barely enough room to accommodate the visitor, both dickheads are pressed against each other pretty tightly, and when you rub both heads through the foreskin in the process of you both getting off, the sensations are myriad and very intimate. The ideal dnouement is obviously the climax of your partner while still wholly wrapped in your foreskin, as you can feel each jet of man-juice blast around the available space in the foreskin, carressing both heads with warmth, often making it balloon out with the ejaculate. If I'm the receptive partner, generally that's all it takes to get me off as well. The clean-up is often one of the best parts, at least to me. I don't think it's possible to end an intimate encounter with docking, it always leads to more, it's almost impossible not to be completely turned on at the conclusion.
Docking was actually part of my very first sexual encounter when I was 16, and it remains near and dear to my heart. It was actually a double-dock, as my lover was uncut as well; once he was in my foreskin, he was able to roll his own over mine. It may not sound like much, especially to a cut guy, but I guarantee you that if you haven't had your foreskin since you were a few days old, you should seek to enjoy the intimate space of someone else's. There's simply no way to adequately express its amazing properties.