I would say I get an upgrade 50%+ of the time, and given that I tend to travel mainly to leisure hotels at peak leisure periods, I'm not sure I should expect better. In India three weeks ago, I was upgraded at 2 out of 3 Oberoi properties - and at the third, the only possible upgrade would have been to one of the four suites, all of which I think were full (I saw the guest list at breakfast).

You know the rule, though - if you want a certain room, book it. Don't hold out for an upgrade, especially if the trip is important to you.