I never had good luck getting upgrades at CPs when I was Platinum but that could have just been the unfortunate property choices I made. The worst was the CP Helsinki where they didn't give me an upgrade, wouldn't allow me a late checkout, wouldn't let us have breakfast downstairs just in the Club lounge which was horribly pathetic (especially after I saw the one of the staff sneeze on the fruit and bread). This is definitely a situation where YMMV I think.