I also have the Amex PRG card, with the annual fee coming due next month. I called to cancel today, and they hit me with a retainer offer for 7,500 MR points now, and another 5,000 when I spend $500 in the next 60 days.

They also informed me that you have two months to cancel the card from the billing date of the annual fee to get a full refund of the fee - else they prorate it and apply it as a statement credit (assuming you have other AMEX cards).

A good way to pick up the 12.5K MR points with some quick spend and still have time to cancel the card before actually being on the hook for the fee.