Adult stockings work best with things people use up or carry every day. Hand cream, lip balm, gloves, a book light and a keychain flashlight are all small and easy to like.
For men, practical picks win: a beanie, a flashlight, survival playing cards. Add one sweet thing, like Lindt truffles, so it doesn't feel like a hardware store order.
For teens, look at what they use now. Sheet masks, lip balm and a Moleskine are popular with many teens, but tastes change fast at that age. Their own Christmas list is the most reliable guide.
For older relatives, keep it simple and comfortable: warm gloves, hand cream, a cocoa set and a box of chocolates. Avoid tiny gadgets with complicated settings, because they end up in a drawer.