Note that even though Platinum status doesn't expire for CdA members, hotels can still see some (all?) of your account activity. If you've had a period of inactivity they may need nudging to give you Platinum benefits (i.e. even more than some hotels need to be nudged anyway).
[I think that this happened to me last year at the Sofitel Heathrow T5. Mrs IMH and I are both Platinum members via CdA, but we'd been crediting stays to her account and mine hadn't seen any activity for nearly a year.]
Last edited by IMH; Mar 16, 2014 at 1:49 pm
Reason: Clearer phrasing (I think).