I am silver,also earned this last year on a CC offer-but qualified again for this year.
I have stayed 6 times last year with various Marriott properties,and I have received an "upgrade"of some type every single stay.Now granted none of these have been an upgrade to a suite,bit usually a higher floor,better view,club level etc..
Since I always stay at some bargain rate(usually thanks to this board)I feel this is just great-and I have reduced my priceline stays as a result.
And yes,I do ask-very nicely at the desk.