This always confuses me, I thought that the benefit was when we check-in, if there are nicer rooms available we get them for free?

But there's is a courtyard that I stay at regularly that makes all kinds of excuses not to give me upgrades. I usually check on the web for the dates I'm staying what room types are available (while I'm in the taxi on the way to the hotel). If it shows a suite, I ask for it at check-in. My understanding was that they were supposed to give it to me.

But this property keeps trying to make excuses not to give me an upgrade, and I'm just curious if as a Platinum I'm entitled to it and should press the issue, or if it's totally at the discretion of the property whether they choose to give it or not.

Some examples:
-At check-in asked if there were suites available he said yes and told me how much extra it would be, I told him I'm gold (this was a while ago, now I'm plat), and he said that they are holding the suites in case any plats show up and wouldn't give me one
-At check-in saw online that a suite was available and asked for it, they said they didn't have any available. I told them online was showing availability. They said they need availability for the full 5-days, I told them that I checked for the 5-day period online, its showing as available. They said they typically don't give upgrades for 5-day stays only shorter stays (???), I told them I had a suite upgrade for 5-days just last week at another courtyard. Then they said that if they only have one suite available they don't give it out as comp upgrade because they like to keep it open in case a paying guest shows up. Finally after all these excuses they did give me the suite.

But should it really be so hard? I thought that if one is showing available online I should get it - always. Is that not how its supposed to work?