We're not ones to take candy from a baby on Halloween, but after Halloween your kids will have a sack full of sugar highs, potential cavities and food items lacking in nutritional value.
Instead, post-Halloween, allow your child to pick a handful of their favorite candy from their trick-or-treat stash to keep and have them trade the rest into you in exchange for a reward (a trip to the park, library, an extra 20 minutes of video game/TV time, etc.)
It'll allow your child to pick a sweet reward that won't result in a trip to the dentist.