I've been HH Diamond for a while, SPG Plat in the past, and will be SPG Plat again later this week.

IMO, the biggest benefit for HH Diamond is room availability for point redemption. It just seems that the rooms I want, and oftentimes they are on short notice, just aren't available until I call the Diamond desk and then they are made available pretty much every single time. Being an HH Diamond definitely makes the points worth more for me.

My experience in the past as an SPG Plat has been that I have MUCH better suite upgrade success than with Hilton. As a Diamond, I've rarely recieved a suite upgrade, and usually book myself into exec or "premium level" regular rooms already, as I don't want to roll the dice... and the price differences are really minor, if at all, so I don't get upgraded much, since I guess "already" am. Go figure.

I may or may not choose to book enough Hilton rooms this year to renew my Diamond. Depends completely on whether or not it looks like I will have a material number of HH points near the end of the year. I stay enough to comfortably keep top tier for two chains each year, and a third if I want to spread the point around. This year, my focus is MR Plat and SPG Plat. Still undecided about HH Diamond.