I agree with communicating with the property in advance. We stayed at SPG properties on our honeymoon as lowly golds and were upgraded at various properties in Thailand. We were not upgraded at the St Regis in Bali (nor given an upgrade offer for a paid upgrade) but they went all out with other honeymoon things like a photo session (they gave us a framed photo, we weren't even offered the chance to buy the extras so it isn't a ploy), room decorated, champagne, cake, etc. we have always noted an anniversary on a reservation and have gotten upgrades or similar celebratory things (tub full of flowers, cakes) on a regular basis. Sometimes I have booked thru Amex FHR so the Amex person had noted it on the reservation but we have always been treated well with SPG.