Seeing as my sewing machine cost more than any of our other electronic equipment, it's only plugged when I'm actually using it...and certainly never if there's a storm around. All other times it's completely unplugged.
I also unplug the computer ...and the tv and stereo equipment....and my clavinova, when there's storms around.
Oh, and they're all on surge boards as well, but I still unplug them in the event of a storm