My buttons are kinda all over but this is the gist of it.

For some of my dps keys my resto heals the tank with the usual stuff, rejuv, regrowth, etc.

For spot healing my resto has seperate keybinds that no other character uses each with a macro like

#showtooltip
/castsequence [target=Druidonename] reset=6 Regrowth, Rejuvenation, Lifebloom, Lifebloom,Lifebloom

more importantly I make liberal use of wild growth

#showtooltip Wild Growth
/cast [target=player] Wild Growth

The mana cost is nothing serious and my dps run out of mana waaaay before my resto so I dont mind using it even to heal one character while im on the move (love all the instant casts on resto druids!)

Gotta run again, hope this helped.

Cheers

PS: if you have a tough boss fight using 2 tranquilities back to back is dirty, just make sure you can keep DPSing on the others not casting it.