Here's the problem, everyone is playing the same scenario map for each tier because said scenario is the 'most fun' or the 'most rewarding' or both. Mythic took a step in the right direction by allowing players to queue for all tier related scenarios in one button press. Unfortunately it still doesn't solve the problem of a particular scenario getting more attention than the others.
My solution is simple: there is one button. You click it and it enters you into the scenario queue. When enough people are in the queue on both sides, a scenario map is automatically picked at random. If you don't like the map, you are allowed to leave, but doing so gives you one 'rage point'. If you get three 'rage points' you have to wait ten minutes before you are allowed to queue for scenarios again. Rage points disappear after 30 mins or so. Kind of like Guild Wars Random Arenas.
This ensures that all scenarios get an even rotation and there isn't a huge problem with rage quitters.