it's a give and take in terms of energy usage. I have my (DPS) rotation set up to where I run out of energy every two minutes, allowing me to use cool head to bump my bar back up into the fast regen range.
In terms of long-term energy usage stability, the best solution is to tone whatever it is you're doing down a bit and always try to stay 60+ energy or at worse, 40+ energy. In my DPS rotation, there is a time when I occasionally just have to do flurry of bolts to allow my energy to get back up before I start grinding away again.
In terms of healing and energy usage, if you really need energy fast and you're in a non healing intensive area, use the channeled heal (can't remember the name) to get back two energy every crit. If you're in a healing intensive time, pop cool head and problem solved! That's what CD's are for anyway =p