I just used the SPG50 for the Sheraton Grande Tokyo Bay for our part of our Honeymoon. The best available rate was 30000 yen (roughly 300 US) or 12000 points a night. I ended up getting the room for $183 a night! Considering $300 is pretty much the lowest anything costs to stay at the Disney Resort, I consider this quite a conquest.
Although they didnt have any non smoking rooms. I'll have to keep calling back to see if I can switch.