I often call hotels directly on very short notice (I'm talking an a few hours before arrival) and get a MUCH better rate than being quoted online or at central reservations. I've not only done this for SPG but many other hotels as well. For example, on Sunday I was able to get a rate at the Sheraton Getway (airport hotel) in Toronto down from $269/night to $179/night within 5 minutes of negotiating^ This past spring I was able to get $110 off a Fairmont just for asking...nicely of course

The one major factor I have going my way is that these are uaually on the day of arrival in the early evening...they start with a rate and I politely ask if they can do better...they give a lower price...then I remind them that it is already in the evening and if the room isn't gone by now it likely won't be and that I would like to give my business. They give another price and depending on the rate quoted I my accept or suggest what I am willing to pay...works almost every time^ My ace in the hole is that I NEVER NEED this room as I always have other options

It is all in the art of negotiating...