I've been using +38 fire/arc sp on my mage along with power torrent. Just wait for the (usually rather quick) PT proc, switch to sp weapon and boom you're at +350sp
It seems like a really nice combo, only downside is power torrents long ICD, 45 seconds. It's not that bad, however, considering you'll have that +38sp from the other weapon as long as you equip it. PT proc is just an additional chance to burst really hard, and that's exactly what you will do when you get the proc. With PT proc I'm able to burst around 2,8k in a global in arcane shatter combo.
Jade spirit seems nice too, it has a bigger proc chance, and seems to be able to be up more than power torrent. That might just be my mind playing tricks, because wowhead comments say that it should be 50sec ICD too. You should try this one out, I haven't tried jade spirit on a 19 yet but if there really is no ICD or it's a lot shorter than PT, this might be a pretty viable option. Even if the CD was 50sec, it's essentially just 62int proc with high proc chance vs 75int proc with a bit lower crit chance.
Windsong is fun for fire but fire is still least viable of the mage specs in terms of dps I think. Hurricane and black magic can be nice, but seriously, I'd rather have a shitload of int/sp, than secondary stats.
For balance druid, I really don't know. I've been testing it out with PT proc from staff, then switch back to mace + offhand, in full intellect set. You can burst A LOT with this proc and starsurge + starfire combo, talking about around 3k global here if you get 2 crits and manage to land the casts at somewhat same time. A lot of burst but casts are still rather slow if you stack 100% sp. Definitely viable option to stack SP + int from gear and go with PT/Jade spirit, you do a shitload of damage but no haste can make it feel really slow paced.
I also tried haste set for boomkin, I'd be a bit around 200sp with +20% crit, 30% haste from gear and windsong enchant. Pop lifeblood, natures grace, windsong x2 and you'll have a good 134% haste for a small amount of time, with 45% crit chance. It's really fun to play, the burst isn't quite as big as with SP set but you'll be able to do everything so ridiculously fast that it's quite amusing to play imo.
I'd say PT/jade spirit with a switch SP weapon for mage, and for balancedruid probably the same or then windsong/black magic.
