I'm pretty new to Hyatt GP elite status (I just became Platinum due to a few MRs), and I received an eStandby Upgrade offer upon booking the cheapest (Mountain View King) room at the Hyatt Regency Lake Tahoe. I was offered an upgrade to an Executive King Suite for $0 per night. As far as I can tell, Platinums aren't guaranteed any room upgrade, so I am not sure why they offered it for free.