I have tried to find any information on what is enough spirit as a resto druid but can't find anything. What do you think is good, all spirit or just some items?
This is for mythic/heroic progression.
Mana is extremely tight during Mythic Progression, don't undervalue it. I would take as much as I could, although if you are using trinkets such as Darkmoon or Candle, I would not replace those with spirit trinkets from Highmaul. Druids don't have something to grant you mana/spirit, such as Elemental Blast for Shamans(I play Shaman). That being said, you don't want to equip items that give more spirit but then cause you lose lots of haste/mastery.
Spirit Neck, Trinkets, Rings, Cloak. Get them all. Then, based on your playstyle and need per fight, you can switch it out for items that don't have spirit if you don't need it on that encounter or even at all. But I would definitely start out with full Spirit slots. I'm sitting at 1186 spirit atm and I'm finding myself running OOM only near the end of fights, so for my playstyle and raid environment it works. Everyone's different, your co-healers are different. You may have to make up more or less than other druids in their own raids, so stacking up until you're comfortable is really the only way to handle spirit.
More spirit to me just means i can be more aggressive with rejuiv coating, and WG spam. If at any point you start consistently fishing fights with more then like 15-20% mana, you prob have too much spi and should drop one slot, or be more aggressive throughout the fight.