I liked using dried cherries with Victor-brand mousetraps. I used a needle-nose pliers to bend the trigger upward, so that the cherry could be secured underneath the fold of metal. The tough skin meant that the mouse would try to work it loose, rather than gingerly licking away peanut butter (the trap would often be licked clean but not set off). One cherry would give a clean kill every time, right across the neck, often with the mouse's teeth still gripping the cherry. One bad year, one cherry killed at least 6 mice. Eventually it just got too old and uninteresting to be good bait, and it had to be switched out for a fresh one.
Hilariously gruesome mouse deaths: They'd live in the storage space above the rafters in the garage (which consists of sheets of plywood nailed to the rafters. I set up some traps near the edge of one of the sheets, and tied strings to the traps, which is a normal measure to take. The string prevents the mouse from wandering away and dying in a wall somewhere, should it get a leg or tail, or just its nose caught in the trap. Well, these were also clean kills, but the force of the snap flung the trap over the edge of the plywood. I came out the next day to see two dead mice hanging, in the traps, from the rafters. My mom saw it too and couldn't stop laughing for several minutes. I guess it was like something out of a bad Stephen King book.