Maybe there needs to be something on creative that gives more options when adding someone to your plot, like just an option to activate things, like doors, levers, etc. I've seen ppl that say they will do tours and check out your plot, but they end up griefing, just a way to stop that. I mean I like to Tour random plots of ppl that are online and I don't grief, but they always have to follow you around opening doors for you.
I saw a grief earlier this morning before i went to sleep. They had griefed a giant castle and turned it into a Parkour course.