I am a Preferred, and most of the time find that it is meaningless. Only in the USA does it come into its own. Usually in Europe they will have the sign, and a queus in front of the sign. Last week in Naples (Italy) there were 14 people waiting to be seen. I wanted to check the car in and get a receipt (a worthwhile precaution in Italy). Fortunately, I always arrive at the airport long before time.

Under the BA Gold card scheme, I am almost always upgraded, or if they can't do that, will charge the category lower than the vehicle that I have reserved.