There was a presentation leaked some two or three years back that the average Diamond spent around 15,000 USD per year. Having reached Lifetime in just ten years, it's obvious that I am spending more than that but I am surprised how much recognition I get when staying at properties I have never stayed at or not stayed in a long time. Park Hyatt Washington upgraded me to their Georgetown suite for a week (confirmed for a standard suite) and I think my last stay with them was about four years back.