We do find we get better treatment as a Platinum.

One time, they just let us stay to 5PM. Another time, they gave us 1000 extra points just for canceling a late check out. We have gotten extra free items from their pantries and some various room upgrades.

Just being a Platinum member versus another random guest shows commitment to the brand and thus a better commitment to you as a customer.

I will also say this: just find a brand or two that works for you and get their best credit card and stick with them whenever you can. It will give you better value and experiences than random cheap hotels from an OTA.