I'd still consider the AGI and STA lines, since those offer the best heal crits of the druid AA's it seems, and since you say you want that to be your best focus.
If you prefer nuking over melee, then also go down INT when you have enough points. If you like the melee stuff in the Warden lines, STR will help that be better.
There's really no one way to do it, although this set up is optimal. WIS isn't really helpful because to take that line you have to give up too many good things that are better in the other ones, IMO.
GL with your duo - sounds like a lot of fun
