Ancien Maestro has posted about using them; either in this forum or in OMNI (where he tipped me off to them). I've not used them, but the ones I have seen at the Calgary Costco were date limited (as in, can't use past February, I think), and were only good at Banff and perhaps somewhere else (Jasper, maybe?). As I recall, you can only use 3 certificates per night, and they are only good for room charges (so you can't use them for spa costs). That's my general understanding, but could be wrong.

Perhaps you should consider PM'ing Ancien Maestro in case you don't get a reply in this thread.