I could be wrong, but having rings increase your touch to a level of 180, still does not use the energy of a 180. And by the looks of it, being a one trick pony of natures touch, to me means you have missed the point of druid play completely.
I find that a large heal allows for more time to regen, for example:
If you are healing a tank with 4k hp, and your heal is 2k, then don't heal until the tank has about 1/2 hp left. Basically, do not heal until you need to. This allows for some out-of-combat time = regen time. Also, if you max bark and embrace (maybe abund) then the time is takes for the tank to reach that 1/2 mark is extended even more, allowing for even more energy regen.
IMO I would reccomend going either Touch based or Embrace based: using those two skills with the strategy noted above can really help you during both leveling and bossing.
As ToeTag mentioned, breath does not start combat mode. This was ver useful before the latest patch, but since the time for exited combat mode has been reduced it is no longer nesassary (casting time for breath and removal from cambat times are equal now I believe). However if you use breath, and need that extra heal, i would recomend it (I personally max touch, embrace, bark, and meditate).
One more trick: casting a skill on someone who is not in combat mode will place you out of combat mode. So, if soemone is watching you kill the boss, or if someone just resed, then casting calm on them is a quick and efficient way for you to leave combat and get a few regens in before you continue healing.
Good Luck bossing,
Regenleif