Prior to 1998 HHonors Diamond level was invite only for the top one percent of revenue contributors amongst all HHonors members.
The year that I made it was rather comical, as they couldn't confirm qualification until they ran some rather complicated reports. Service as a Diamond was superb, always a suite or best room in house.
Once it became a published benefit, many others have qualified, and I feel that the service level has diminished somewhat.
For me it would be fantastic for a super HHonors level: 1999 200+ nites, 2000 140 nites.
I still get great service from the Diamond desk, but some property managers make me want to scream.