I have a few ideas.

1) Instanced Dojo.
During prog for the latter phases of Ultima Weapon, my team started using Binding Coil Turn 4 as a practice area. This was possible because the whole arena is accessible without triggering combat, and its size was roughly analogous to Ultima's arena.

Instanced Dojo is a suggestion that sort of expands on that. In an instance let us place dummies that can act out mechanics, dps checks, set markers, set timers, etc so players can put together practice stages for fights.

2) Class Halls
Like in WoW; have class halls with associated class campaigns and other reasons for it to be a possible player hub. Past that the real reason for its existence is to be a hub for players of the same job to congregate. The hope and intent is to stimulate conversation between players ingame and provide practice dummies for players to help each other improve.