Seat block - IME it is hit&miss. I guess there is some kind of policy, but also some glitch to make it fail on many occasions. Possibly OLCI or CI-agents can override it? Or perhaps it is only supposed to work in Y?
Recently in 2C, on A320 where all middle seats are supposed to be blocked, two non-status pax got seated in 2AB when row 3,4 and 5 was completetly empty. Purser saw the situation and suggested to 2AB to move to row 3 after take off. But a really strange seat assignment.
Priority to select meal - During a period I and other status holders were always asked food preference first in the cabin. This seems to not be the case anymore. Lately I've found 'Food-preference-asking' starting with 1DH and working its way back. Perhaps they do the prioritizing in the galley afterwards.
Status acknowledge - Sometimes purser aknowledges my status (which I really appreciate, but I know many thinks this is not a perk or even annoying). I have found it to only happen with "the good" pursers, ie those who generally are committed to their work and in harmony. Usually just a discrete "Welcome back", "Good to see you again" or "Thanks for flying with us today".
Upgrade clearing - I have once had a upgrade clear despite no availability. However, it was on Euro-C so I'm not sure it has any relevance.
Bend-ze-rules - And the most strange type of benefit I've come across (and I'm not really sure it even exists): On at least 2 occasions I have called AY+ service centre and asked for a small bending of rules. For example: "My bag is a tad bigger than the allowed 158cm, could you allow it?" and have been answered
"No, the rules are the rules. But you are platinum so I'm sure CI will allow it". I have been baffled every time I get this re-assuring but uncommited answer, but so far it has worked.
I don't know if service centre staff just thinks "surely everyone in our organization must care for our frequent flyers" or there really is an unofficial widespread rule of being tolerant towards FFs. Some parts of AY certainly does not cut plats any slack (yes operations, I'm looking at you)
And a note about an official perk:
Seat selection - I'm usually in J (where seat selection is free for all) but the few times I'm in Y it works just fine. However, the most attractive seats (for me) are always blocked off, ie the 2 first rows of Y. Maybe because curtain will move
Also, a few times in J I have been bumbed out of my selected seat for no apparent reason. NB not for operational reasons, it is just that checkin have assigned my seat to someone else.
I have even been bumped out of a selected seat just to find the original seat empty at checkin. I asked and got back my seat, but was met with "the evil eye" from seat neighbour once boarded.