I think that a good way to solve many problems with griefers is to add an option for admin and ops that allows all or certain users from building on the map. That way, by default, new users could not build but could still explore and view the creations without being trapped in a prison. Then the decision of whether the user can build or not relies on the admin or op. If this idea was already posted, then I apologize for cluttering the forums with an extra topic.
While I think this has been posted before, it's no matter. I think this idea is pretty decent but has room for improvement. Maybe some sort of timer? Also, players who the admin/ops personally remove the tag from should be whitelisted so that they can build any time they come back to that server.