As a kid, I loved Halloween. The costumes, the decorations, the pumpkin carving--it was really all for the sake of hauling in a huge bag of candy that would last until Christmas (when another mother lode of goodies arrived). As a parent of two spawn smack dab in the middle of the Halloween (read: candy) obsession, I revert back to the tricks for the treats my own parents taught me.
First, on Halloween night, it's important that only a few pieces of candy be eaten by the Spawn. You don't want them whacked-out on sugar and getting the jump on you. You'll never get them to bed. Just give 'em a taste, one or two pieces perhaps, but no more.
You should also force them to combine their bags of candy loot together and then take turns picking out their selections. As the parent, it is your right--nay, your duty--to tax the Halloween candy haul. This teaches the Spawn a valuable lesson in life: every bit of their hard labor will be heartily taxed by an overlord.
Second, when you tuck the little sugarplums into bed that night, slide your hand underneath their pillows. If they are angels you won't find anything. However, what kids--fueled by the temptations of all that candy--will be angels on a night of demons, witches and goblins? Most likely they will have sneaked some pieces to bed to eat after dark. You must be vigilant. Exorcise those demons.
Third, once they're sound asleep, it's time to raid their candy bags. Only take a few pieces and make sure it's second and third tier candy. If they question where a specific piece went the next day, tell them that you did all you could to fight off the ghosts and goblins, but they wanted some too, and, well, who were you to argue?
Finally, it is important to let them have a candy feast. Plan ahead as the next few hours and next day will bring a sugar high with the inevitable detoxification. Let them eat as much as they can, with the rule that the rest gets put away and maybe even thrown out. You don't want old candy sitting around until Christmas.
Besides, if your own spawn are anything like mine, they've taken the precaution of hiding a few caches of candy around the house in preparation for the purge.