Lets say you were the class design guy for EQNext....

[Nocte]

This list isn't thoroughly thought out, but I kind of liked the general idea of how EQII did classes/subclasses. This is my take on that. I'd like to see multi-classing ability within a specific archetype (rogue/priest/caster/tank) and alignment (good/neutral/evil).

Casters:
Summoner (pet class) - good/neutral -- [summons elementals]/[summons monsters]
Cultist (crowd-control) - neutral/evil -- [curse-based spells]/[necromancy]
Arcane (nukes) - good/evil -- [fire & air]/[earth and ice]

Rogues:
Thief (utility) - good/neutral -- [bard-like with utility]/[swashbuckler, flashy moves, lots of utility]
Assassin (melee DPS) - evil/neutral -- [poisons, stealth]/[burst damage, gadgets]
Ranger (ranged DPS) - good/evil -- [animal companion(s), bow/melee auto-attack]/[traps, bow/melee auto-attack]

Tanks:
Knight (armored tank) - good/evil -- [paladin]/[shadow knight]
Monk (avoidance tank) - good/neutral -- [tranquility: less dps in favor of amazing avoidance. no auto-attack]/[patience: dps with precise burst damage attacks. no auto-attack]
Berserker (DPS tank) - neutral/evil -- [axe-throwing, AE melee damage]/[leaps to target, AE melee damage]

Priests:
Cleric (reactive heals and AC/HP buffs) - good/evil -- [courage]/[fear]
Druid (heal over time and haste) - good/neutral -- [plant-based]/[storm-based]
Shaman (ward healing <see EQII> and debuffs) - neutral/evil -- [ancestral/spirit-based]/[poisons/disease]