In the US, Diamond, Titanium or Globalist doesn't give you much. In Asia and sometimes in Europe, the higher status will give you better upgrades. I have never received any special upgrade as a Diamond overseas in Europe/Asia, typically just executive floor and lounge access. Globalist is a hit/miss depending on the property. Marriott Platinum (pre-SPG merger) sometimes resulted in suite upgrades. But since the merger, I imagine Titanium is also dime a dozen.