We inherited a safe when we bought the Lodge. It was locked, and we had to write to the safe company for the combination, which we discovered was unique to the serial number of the safe. You learn the most amazing things when you begin innkeeping....
Alas, there was no treasure once we got it opened. It was a Geraldo moment.
Anyway, we keep our petty cash in it, along with our passports and foreign currency from our travels. We keep enough cash on hand to make change for guests, and that's about it. We've never had a guest ask us for a place to store valuables or money, and we don't advertise such an amenity. Shoot, sometimes we forget to give guests their key, and the forget to ask us for it.... We never lock the safe. It's basically fire protection. It's not in any place were people could see it.
Around here, people think you're peculiar if you lock your car door. There's an old joke around here about the only time people lock their car doors when going to church is in August, and that's so their neighbors can't leave a bag of zucchini in the back seat.