The American Express Platinum card was first launched in 1984, to celebrate the 40th anniversary there are a number of limited time AmEx offers for Platinum cardholders:
Hilton: Spend $180, get $40 back. Valid until 7/31/24
jetBlue: Spend $200, get $50 back. Valid until 8/6/24
Delta: Spend $180 via Amex Travel and get $40 back. Valid until 7/5/24
Hertz: Spend $150 and get $40 back. Valid until 6/30/24
Some nice deals above, as always can be stacked with other offers to make it even better.