We’ve already mentioned in our 42,000 with the Amex Platinum Card post that you can get free OneWorld Sapphire status with that card, but its a good enough benefit that its worth calling out in its own right.
If you take out the American Express Platinum Card, you can immediately receive Cathay Pacific Marco Polo Gold status, which is OneWorld Sapphire and the equivalent of BA Silver. The major benefits of this card are that it gives access to OneWorld lounges even when you are not flying in premium cabins, and also allows you to select seats for free in advance of Online Checkin – other passengers have to pay up to £80 to book some seats.
Note that if you already have OneWorld Sapphire or equivalent status, it is worth holding off applying for that specific benefit, as it is not yet known whether this is a one-year only deal or whether it lasts for as long as you have your Amex Platinum Card.
The full list of OneWorld benefits can be found here.