My experience has differed from bhrubin. Been SPG 100 for 2 years.

I get suite upgrades at Sheraton, Four Points, Le Meridien, and Westins. Never got a room upgrade at the Regis or LC properties.

I think it really depends on your ambassador. My ambassador is not very pro-active. The only e-mails I actively receive from my ambassador is when she will be taking time off. The one time I asked for special assistance, she just told me it is up to the property's discretion.