I gave this some serious thought before mapping out my plan, mainly because what seemed like the way to go was quite different to conventional wisdom.
To begin with I maxxed out Improved Natural Wisdom, I did this because I wanted the option of swapping out Wis gear for HP and Mana and focus items. I had one point left over so stuck that in Natural Run Speed, although for a Druid I think this is a waste of time given the number of run speed spell options we have.
I then maxxed out Mental Clarity. Mana regen is my main focus, everything I am working toward is to get the maximum mana regen possible. I see this as the foundation to everything I want to achieve with Celeni. The way I see it mana regen is more powerful in all situations, mana efficiency comes next.
I am now working on Spell Casting Fury, although the Archtype level is not particularly impressive with just a 7% chance of a crtitical blast, it is necessary to have this in order to get the Planar Archtype Fury of Magic, which really does start to produce the results.
Next I will probably work on Spell Casting Mastery, for the reasons mentioned above, an increase of 30% chance of specialization kicking in is worthwhile from my point of view. It will then be a toss up between Dire Charm and Quick Direct Damage.
Although I would love to have DC to mess around with, QDD would be more practical as most of the time Celeni fills the wizard role in our groups. Primary nuke damage, with back up healing.
Given that she has good healing focii and Alt specialization, the concetration now is on bringing mana regen and nuking capability up to the best possible level.