Personally I think you will be better off on Accor or any other of your statuses. Many hotels seem to have that policy of "upgrading" to a higher floor as the member perk. Auckland is one of those, and only if you book one of the lower categories. If you book a higher category, "there is no better room" to offer you, ie suites are not considered for this upgrade.

From personal observations (ie I could be mistaken), it seems Cordis Auckland do value repeat customers more, so if you frequently stay at that particular hotel, you are much more likely to get a decent upgrade than as a 1865 member.