American Express currently has two limited-time offers on their co-branded Hilton Cards. These offers can earn up to 100,000 HHonors Points! Both offers expire on 5/4/16, so apply ASAP. See below for details on these offers.
If you already have the no-fee card, you can upgrade to the Hilton Surpass card ($75 annual fee) and receive 100,000 points after spending $3,000! Simply log into your American Express account, and you should see a link to the offer above your current Hilton Amex card. If you upgrade your card for this offer, it should not result in a hard credit pull. Again, this is the highest offer I have ever seen.
Since American Express has implemented a “one bonus per product per lifetime” policy, we definitely recommend taking advantage of this offer while it is available!