Wattage is really a calculation done with resistance and volts. It's basically like driving an automatic car instead of a stick shift. Your coil resistance and volts combine to make watts. Once you set a device to the watts you want, it doesn't matter what your coils resistance is. The device will adjust the voltage it puts out to create the wattage you set it to. To save on power with a device capable of variable watts, I would adjust the watts to taste, and then get a coil with lower resistance. Your device will then adjust the volts it puts out to adjust for the lower resistance of your coil and you'll get longer battery life.
My new tank came with a handy chart (Hypertank...amaaaaazing)
1.7-1.9ohms / 3.1v-3.4v
I use 2.5 attomizers and usually have my voltage between 3.8 and 4.0 on all of my mods.
My name is Jess, and I'm a magpie...Oh Shiny!
I took a one way Nicoticket to ReoVille with my ProVari like an MVP!