This may have already been said, but I didn't see anything about it on the magic eraser tag so I figured I'd share. Magic eraser is the best way (and only way, that I know of) to get sharpie marks off your nice white countertop.
It takes Sharpie off of most things (but if it’s a painted surface, it will also take some of the paint)! Think of a Magic Eraser like a microgrit sandpaper. It’ll get most things to go away, but you need to be careful what you use it on.