For PVE healing and large scale pvp such as alterac valley I use healbot (with decursive ofcourse for cleansing) for the "unitframes" and CT bars for the actionbars. Dr Damage isn't vital but it's pretty nice for additional spell information.
Healbot is pretty awesome, gives you a rough estimate how fast people are dropping on health and incomming heals on them etc. Basically you can just leftclick heal everyone without having to think too much of it since it'll use what heal it consider the best for the given situation. You can also config different mouse / key combinations to do different stuff like holy light is default to mouse2 and alt+mouse1 is cleanse.
Librameister for automatic libramswitching during heals and pallypower for buffmanagement.
I'm currently trying to figure out what i should use for PVP aswell, especially the arena. Currently im using perl & proximo mainly. I want to get something that tells me duration of debuffs like blind and stuns on my teammates and enemy cooldowns on kick / counterspell. And all this without having the screen cluttered with addons would be nice haha.