Yes, I think it was working with the "higher-ups" at Orient Express (making a point of my birthday) when planning the trip that did it, coupled with the fact that we were one couple at a lower travel season when there were several travel groups in the hotels at the same time. I've tried as well elsewhere and it's pretty hit-or-miss.
I've found that simply being nice helps a great deal. So many people arrive at their hotel stressed from travelling and as a result aren't necessarily nice to the check-in staff, so those who are nice do stand out.
As others have pointed out, corresponding with the GM or the hotel group in advance is also helpful. I've found it easier to get upgrades when they were for my travel companion (e.g. when I was surprising my girlfriend for her birthday). But I think the birthday thing only works when it actually is someone's birthday (remember, most places have your passport on hand to check!).