If my understanding is correct each is good for a stay up to 7 nights. They are pretty much useless now as most hotels don't have clubs open in North America. After stalking a few threads it looks like a few of the Hawaii properties are having their clubs open by mid July - however - they are not allowing you to actually book into a club room, rather, are opening the clubs for those Hyatt loyalists that are Globalists that get the club included in their stays at this property without needing to use a certificate.

A good rule of thumb I have heard from others is when you go to book at a property, see if they are selling club level rooms for those dates. Then you should be able to book the base room and call to have the certificate applied and get upgraded to the club level room. However, if they aren't selling club rooms for those dates chances are you cannot use a certificate during those dates; but you could always try and call and see what happens.