Bloodshot - there are different ideas on this - but I was told by GPCS that Plat IS 2 nights + 2 upgrades, while Diamond is 2nights in suite. The difference (according to them) was that you cannot be turned down for use of a suite in the 2nd scenario, while the upgrades for Plat work like standard upgrades...ie- there are hotels that won't take them, they can't be used on an award stay etc.