I did read a post on the wow forums, tho it was for mages it was kinda good. He described the best gem's to put in ur gear for maximal %dmg. There is a difference bitween pvp and pve tho, but his post was about pve. He recomended, put +spellhit gems untill u have around 16% spellhit with talents, after that +spelldmg. Critgems didnt boost ur dps as much as any of these two untill u had about 1200+ spelldmg and 16% hit.
Something like that, as i said, this was for pve. For pvp depending on ur gear, if u have full arena gear + weps + extra epics, ur reciliance and stamina should be so high that u dont really have to aim for +stamina gems, and can instead focus on +spelldmg and/or resiliance sins ur basecrit % will be high, i gues the druid is boomkin? :P

// Emo?

[Edit] Changed 17% -> 16%