Nah, I travel a LOT and am typically in a different hotel each week. In over eight years of doing this, I've never hidden my stuff and never had reason to regret it. If you think about it, the house keeping staff are the last people you need to worry about. They KNOW they are going to be the first person suspected if something goes missing and would have to be nuts to take something.
Besides, at the risk of sounding naive, just because they don't make a hell of a lot of money doesn't mean the cleaning staff are likely to turn to a life of crime. From what I've seen, most are single mothers doing their damnedest to make a living and they aren't going to risk their job to swipe your skirt. ;-)