If you are worried about theft, just leave the DND up for the duration of your trip. Unless I'm going to be somewhere for a week, I never have them service our room. Not that I'm worried about theft, I'd just rather not be bothered with them being in the room at all. I really don't need the bed made and don't usually mess up the room enough to need it cleaned. If you need towels, just call the front desk and request new ones.