An occasional 100k Amex Platinum offer appeared yesterday and is still working. The bonus is only for those who have not had that card before.
Disclaimer: I am not compensated by Amex for use of this or any other Amex link on this blog.
There are other versions of the Platinum card that you can collect the bonus on each. The Mercedes-Benz version has a highest-ever offer of 75k valid for application through 6/22/16. Previously the bonus has been a steady 50k. Appy here (thanks to FrequentMiler Quick Deals).
The card is nearly identical to the regular Platinum. The Mercedes-Benz logo is stenciled on as if done at home. The annual fee is $475 instead of $450. At card anniversary you get a $100 certificate for spend at Mercedes-Benz dealers, which stock logo gifts such as pens and shirts.
You can hold multiple Amex Platinums if you want both bonuses. Same-day applications should work, one will probably go to pending and take a few days. These are charge cards, not credit cards so do not count to the 4 credit card per person limit that Amex has had, though recently is relaxing.
A different strategy is to hold one different Platinum card each year for its benefits. In that case you might not get such high bonuses though may do better overall if you use the benefits.