After losing things in hotel rooms over the years, I learned a critical rule: be careful about spreading out.
If it’s just a one-night stay, I unpack immediately after arrival, but almost everything stays in two places: bag open and on the floor with the clothes I need for the next day. Laptop on desk with mouse, chargers, etc. directly next to it. Wallet and passport go by the laptop or the bag—nowhere else. A longer stay might acquire a third space for stuff, but no more.
At night—or in the afternoon if I’m jetlagged on another continent somewhere—I sleep with my iPhone and watch by the pillow. The phone doubles as the alarm, so I’m not likely to forget it. Upon waking, I immediately move both items to the desk with the rest of the stuff.
Before departure, I do a quick sweep to make sure I haven’t forgotten anything obvious. But if I’ve done my job right with the minimalist unpacking, it’s not even necessary.
Of course, then I leave my credit card at the restaurant and the iPhone in the taxi—but those problems require different solutions.