In vanguard the classes are divided into four archetypes (Offensive Fighter, Protective Fighter, Healer, Caster). When scheduling an event it's often nice to specify the archetype needed instead of the class, as it often won't matter what kind of tank, dps or secondary healer you got. Would it be possible to integrate the archetype hierarchy into the event scheduler?
Alternately a roles concept could be possible where people decided what role they wanted when signing up. Since some classes fit different roles depending on their skill/ability choices that won't lock people into choices. E.g. will Shamans take on slightly different roles (main healer, secondary healer/dps) depending on what choice of form they make. With roles a shaman could sign up for both main healer or secondary healer if he wanted (or tank for that matter, but he would be properly flailed if he did
As an event planner I would then like to specify an event with, for instance, 2 tanks, 2 crowd control, 1 main healer, 2 backup healer, 5 dps. People could sign up with in the role they wanted (with a specified character) and it would be up to me to approve them for that role.