Water pumps, electric water heaters, heat pumps, electric heat, are often some of the largest draws.
During an extended power outage, we turn off the h/w heater and water pump. The water will be quite warm for a fairly long time and there are other ways to warm water.
We have a 12k portable (okay, rollable on wheels or lifted by front end loader on sling) generator that supplies 240V but do not often use it during power outages.
Outdoor grills, propane cooktop, and gravity flow water- albeit about 1/2 pressure, so baths, not showers, which works better for adding buckets of hot water when necessary.
Also coal furnace and stove that do not require electricity, though the blowers won't be on, fridge/freezers stay cold for long times if not opened, but then it is usually winter when we have outages, so pack outside (for extreme outages) or simply fill ziplocks with snow/ice and pack in fridge/freezers.
Camper fridge can run off propane with minimal battery usage, so that is an option, too.
We've found 30-45min runs of the generator when absolutely necessary is enough to keep fridge and freezers cool indefinitely.
Just be sure to avoid multiple hard start items (like compressors in fridge and freezers) starting at the same time. Staggering by plugging/unplugging about 5 mins apart is plenty of time.
Backfeeding a house requires a lockout method, such as a transfer switch or a physical lockout plate installed on your breaker box. You should also have 240v generator, else you will likely only have power to about HALF your circuits AND could DAMAGE any 240v items.
Additionally, not providing enough power for electrical items running can cause damage to both the appliance and the generator.
But the BIGGEST KILLER of generator use during power outages? Cabon Monoxide! Don't run them indoors, near open windows, confined spaces, etc, etc.
Incidentally, those who use heating oil as a heat source can use offroad diesel fuel for heating, too. You can have a backup tank of 250-600 gals quite easily and can run your farm equip, main house heating, diesel generator, etc.
You can also use an inverter in your vehicle to recharge/run small items while you drive for fuel or other supplies. Can also use 12v chargers for cell phones, etc.
Lots and lots of ways to go without power for extended periods, with money and comfort being the limiting factors ;)