The diamond guarantee is worthless if you ask me. I had a client call on a Tuesday midday requesting an 8 am Friday meeting. This meant I needed to fly there the night before, so I needed a Thursday night hotel room. All the local Hiltons were full. I called the Diamond desk and tried for a Diamond force. No go.

You have to make the reservation before midnight of the day that will be 48 hours before the first minute of the day that you will check in. So if I want to check in on Thursday, the reservation must be made 48 hours before it turns Thursday.

If you read the terms, it certainly sounds like you could make the reservation on Tuesday for a Thursday check in, but it is not so.

I have succeeded in getting a diamond force a week or two before the stay, and I am charged rack rate.