If my kit's left in the room, it's in its bag, usually under the bed or in the wardrobe. Then again, we usually stay in the same small, family run hotels which are (IMO) far more secure than the hi-rise types.
A few years ago, when we were on Crete, I left my (compact) camera on the seat of the open topped Suzuki Vitara for a couple of hours and it was still there when we got back to the car. Parked in the middle of Rethymnon. Not sure I would do the same with the D800 but I didn't leave the compact on purpose.