A 'well planned' tank should have no problem coping with the average power failure we see. In reality, most tanks should/could easily survive 6 hours without power.
Smaller tanks may require some insulation to retain heat (simply wrapping a blanket around can radically decrease the speed of decline).
Some fish with higher o2 requirements may require some extra water movement, but trying to keep return pumps, and powerheads is by no means necessary. A simple / cheap battery backup airpump installed as an airlift will provide more than enough circulation / surface aggitation for even these sensitive creatures.
One could theoretically plan to power a heater, but I wouldn't try to maintain your 'normal' temperature, keeping a temperature of 72-74 should be adequate for survival for the majority of creatures. Once power's back on bring the temperature up slowly.
Longer term powerfailures, yes would require some forethought - but lets face it, the majority of canada is rather unlikely to see hurricanes, or major natural disasters... Well other than vancouver sliding off into the pacific - but at that point I don't think y'all are going to be thinking about your tanks
I don't see much need to spend thousands on a generator, or huge UPS system, in a vain attempt to keep the system as a whole running. Provide the basics and be patient for the lights to come back on. A situation of hours without electricity is rare - why get stressed about it?
Andy