Op - are you staying at the same properties again and again? If so, I encourage you to talk to the GM about the lack of Diamond amenities during your stays - sometimes they just need a proactive nudge. It’s quite easy to know if there are room categories higher than the one you booked - just look at available rooms during your dates with a search before check-in. If there are higher category rooms available, ask if you can upgrade if they didn’t proactively do it for you.

Most places do have a higher category room like corner room, higher floor, view, etc. Not every hotel has a suite - and those are hard to come by. (Easier when suite upgrade was listed for Diamonds a few years ago.) Anyway a while back, I was having repeated stays at a Hampton and they always proactively put me in their larger rooms (the ones with a hot tub), but the property didn’t have any suites. That’s the best it was going to get. Since everyone gets free breakfast, the amenity is water and a snack.