My favourite approach is the LGW:
* Call for people with disabilities and infants under 5
* Call for passengers in the Club Europe cabin (the amount business UKs pay they should get to go first too imo)
* Call for our most valued customers (Golds and Silvers & Oneworld equivalents)
* Call for rear rows with a reminder that Club Europe and Status customers can board at their leisure
The LHR approach works fine for Glasgow flights where people respect the system. Italians (for example) appear to think that they all should use the Fast Track Queue(!)
And GLA gate 19 is undoubtedly the best by far and will be missed with the switch to the ex-BD lounge.