Actually,in the past I used to make an effort but I have stopped. Too many problems have occured because of crew or ex-crew. I have had crew get so drunk onboard that I had to ask them to be more quiet as the other pax were complaining and then they were gossiping about their airline so loudly that everybody around them could figure out that they were cabin crew. I just had a run in with an ex-BA cabin crew,who actually asked for a comment form because apparently it is our fault that his seat has too little legroom for him and that he didnt get an aisle seat!At the end of flight the loser changed his story and told our purser that his seat was broken and we just ignored it
.Some crew are just an embarresment. I do make an effort if I know them only but that is it. In my airline (EK) we are not allowed to upgrade staff anyways,only our groundstaff has that authority. I myself have never had a seat in a premium cabin and I have been working here for 7 years....I hear LH is pretty good with upgrades.