Originally Posted by projectmaximus

Check-out date is what matters for Hyatt in terms of timing for a promo, EQN, and whatever else there might be.

As for combining, I'm not referring to at the property-level, but for Hyatt program's purposes they will treat it as a single reservation only. eg, when they offer a bonus for a certain number of unique stays, all the nights at a single property even if made over several reservations will only count as one. Or if you have a month-long stay and it checks out the day after a promo period ends, you can't get it to count by simply splitting into two reservations, you need to actual end the night before and change hotels or Hyatt will count it as one stay.