This year (2017) is my first time ever having Platinum 75. Before I was always normal Plat 50.
There are only incremental differences. The extra Star-point when you stay at SPG hotels is welcomed. The YOUR 24 requires hotel approval. I used only a few times (less than 5). I did get approval for a one-night stay to check in at 10:00pm and check-out at 10:00pm in Seattle. Well. I checked out at 12:00noon so not much story.
If I use it on vacation - like a 5 night stay. I found I cannot say I check in Day 1 at 10:00pm and check out Day 5 at 10:00pm. It can only be used on Day 1 - which neutralizes the YOUR 24 abilities for multi-night stay. The hotel I tried this on was the Westin Tokyo. I was given a 4:00pm check out only. They did give extend it to 5:00pm on departure day due to my airport limo bus schedule.
I want to believe I have a slight leg-up against Plan 50 when I use Suite Night Awards. I believe (but not officially verified) who gets the upgrade have some factor to do with how you're paying (paid stay, cash & points, or points stay) and what status level. Plat 100 has an SPG ambassador calling the hotel for upgrades and Suite Night Award upgrades. Hotels probably yield to them.
I do notice this year, I was able to use almost all my 10 suite night awards (1 night left). In the multiple years past as Plat 50, I used it in similar hotels and the success rate was definitely lower and I normally have 3-5 Suite Night Award goes waste each year.