Correct me if I'm wrong, but I never quite understand people who post how they were looking at the hotel website at check-in to spot available suites etc. and then insisted on those rooms for upgrades.

Because doesn't each hotel decide what type / number of rooms they put in their upgrade pool? So if they have 20 executive suites but designate only 5 as upgrade inventory, how can anyone determine from the website whether he/she should be entitled to an executive suite upgrade even if those suites appear as "available" for regular booking.