For anything less than 2 weeks I usually leave it unplugged, mainly because I'm paranoid that something goes wrong with the charger and starts a fire. But I also turn off the water, hot water heater, ac, heat, etc. For similar reasons (unless the forecast is close to freezing and then I leave the heat on low)
When my parents left for a weekend to attend my wedding, they came home to their basement flooded from a burst valve... So I've learned by example