The 4 piece bonus is very nice when you have the opportunity to stand and cast, and aren't being hit. I suppose the trick is to create situations where this is true. One big problem I had was noticing when the bonus procced. I wanted a noise like the clearcasting proc and after looking around for a while I couldn't find exactly what I wanted. So I wrote a very simple addon to do it for me, and it's been working very well.

I created these three files:
BalanceProcs.toc
BalanceProcs.xml
BalanceProcs.lua

The aura names in the .lua file can be altered based on class, and the number of 'ifs' can be increased or decreased. The built-in sounds for PlaySound are at API PlaySound - WoWWiki - Your guide to the World of Warcraft and the sounds for PlaySoundFile are at API PlaySoundFile SoundList - WoWWiki - Your guide to the World of Warcraft and API PlaySoundFile SoundList2 - WoWWiki - Your guide to the World of Warcraft (in case anyone wants to do something similar).

-- BalanceProcs.toc text --

## Interface: 20400
## Title: BalanceProcs
## Author: Peaceflower
## Version: 1.0
## Notes: Plays a sound when Nature's Grace or Wrath of Elune procs.
BalanceProcs.xml

-- BalanceProcs.xml text --

<Ui xmlns="http://www.blizzard.com/wow/ui/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.blizzard.com/wow/ui/
..\FrameXML\UI.xsd">
<Script file="BalanceProcs.lua" />
<Frame name="BalanceProcsFrame" hidden="true">
<Scripts>
<OnLoad>
BalanceProcs_OnLoad();
</OnLoad>
<OnEvent>
BalanceProcs_OnEvent();
</OnEvent>
</Scripts>
</Frame>
</Ui>

-- BalanceProcs.lua text --

function BalanceProcs_OnLoad()
BalanceProcsFrame:RegisterEvent("COMBAT_LOG_EVENT_UNFILTERED");
end
function BalanceProcs_OnEvent()
if arg2 == "SPELL_AURA_APPLIED" then
if arg6 == UnitGUID("player") and arg10 == "Nature's Grace" then
PlaySound("PVPTHROUGHQUEUE");
elseif arg6 == UnitGUID("player") and arg10 == "Wrath of Elune" then
PlaySoundFile("Sound\\Spells\\Clearcasting_Impact_Chest.wav")
end
end
end