World of Hyatt Visa card members will receive a 10% points rebate on points redeemed from July 1 – September 2, 2019 for free night awards, Points + Cash stays, room upgrades, dining and spa experiences, Exhale fitness classes and spa therapies, or FIND experiences.
Points redeemed for Avis car rental certificates or points transferred to airline partners are not eligible for this promotion.
Points redeemed for a stay require the entire stay to be completed by September 2 to be eligible for 10% points rebate.
Main thing to consider is whether rebooking existing reservations is feasible to take advantage of this promotion. That is no issue if the same room type is available for your dates.
A much bigger deal perhaps if you have a WOH suite upgrade attached to your stay reservation. I lost a suite once on a 3-night stay by screwing around with the reservation a couple weeks before my stay to take advantage of a promotion and the telephone agent was unable to rebook a suite at the hotel.