I'm a humble Plat member and I've got a question regarding the use of points or upgrade certs to upgrade a paid reservation to the Club Floor. First of all, can this only be done at check-in or also in advance? Are there any time limits for that e.g. only maximum days prior to check-in or can the upgrade be confirmed anytime?

Also, if the hotel offers e.g. four room categories such as standard/deluxe/Club standard/Club deluxe and your booking is for a Deluxe room, would you get upgraded to "Club deluxe" or only the "Club standard" room using your points? Let's assume that the deluxe category is the same layout/size etc for both "normal" rooms and "Club" rooms. IMO, you should get the same room type you have paid for but on the Club Floor, right? Why else would you pay for a more expensive room type in the first place if you get upgraded to a standard room in all cases?

Does this vary by property or does GP have some clear T&Cs when it comes to using points for an upgrade?