PB is the best of the simple baits. However, it does have the disadvantage that mice are sometimes able to eat it off the trigger without springing the trap. When out in the field, taking a survey, I use a mix of peanut butter, bacon grease, oatmeal, and raisins. Location is also important. set the trap with the trigger end up against the wall and you might not even need bait.
You might also want to investigate glue traps. Like the snap traps, they work best when set along the runways.