I have a couple of Platinum Extras certs. On one of them (I think the one I received for qualifying for Platinum), the choices underneath the heading "Hyatt Hotels & Resorts" include Regency Club upgrade. So it appears that it's available for use at Hyatt Hotels AND Resorts. The fine print on the back, however, says not available at Hyatt Resorts. Anyone else notice this?
Based on what I've read on the forum it seems like it wont work at a resort, but I'll bring it with me to HR Maui anyway and see what happens.