Just after 9/11 my wife and I retired and traveled a lot. As a diamond, I was upgraded frequently. But the most astounding upgrade was at Hilton Marco Island---- booked the cheapest room, which was absurdly inexpensive in the wake of 9/11 ($60/night??). We were upgraded to a huge suite.
Of course that was back when having diamond status had far more impact on the front desk than it does now.