Overnights can be very rewarding. It's nice to wake up with a receptive WG by your side .... it's difficult to call for one in the morning.
All the info re safes, etc., just makes sense, and works well, but I would add the need to be in a secure hotel that prohibits strangers wandering the floors at all hours. Not a nice experience to wake up after your WG opened the door to let in a couple of gorillas ... standing over your bed demanding you open the safe, give up your pass codes, etc.
I've never had any issues, but I am careful. Even to the point of never drinking anything I haven't opened / controlled in my room. There have been extreme cases of punters (all over the world) not waking up because a WG has slipped too much into their drink(s), which can be exacerbated by alcohol.