I remember one time Mrs firstlight was on a separate booking but sat next to me (gold) and at the time was silver; she was offered the same complimentary drink as me. Also she got greeted as well.

Now we've both managed to become bucket and spade GGLs; in ET one time we were ignored, another time we both got champagne and nuts. Twice the greeting to me travelling alone in ET has been quite subtle and by name only. It's very inconsistent, might depend on the flight length, just adds to the fun.