1. Figure out what you would need to survive for 1-3 days.
2. Figure out what you would lose money on in such a situation. In an emergency you should be prepared to absorb some losses... it's life that you must preserve, not luxuries. The ice cream can be replaced. You might need the beef, though.
In general, you can run a few lights with any generator. Beyond that, you should probably add up your Fridge and freezers to the extent necessary to support survival. Even portable heaters consume HIGH wattage, but at least one is needed in winter (figure 1500-1800 watts for that alone)... don't plan to try and run a heat pump in winter or summer. If you are on a well, you should have a means to connect the pump for water. For cooking, I'd go with the outdoor grill.
That's really about it.
Go with a gas generator - generally 3000 to 6000 watts. Propane or Nat Gas models are available, but you have to have a reliable source of whatever fuel you need... which might be tricky in emergency situations.
One more note: if you're trying to run a bunch of devices at once, you'll need extension cords and splitters that can handle the amps... but generators usually only support 2-6 devices at once, and that's a reasonable guideline to work within... don't go nuts or you'll have a fire hazard on top of everything else.
Rather than trying to heat with electricity, put in a woodstove. Much more practical.
If summer conditions are unbearable without AC, designate one smallish room the summer refuge and run a window unit in it. Figure its consumption (high) into your load requirements.
BTW, largish generators burn a remarkable amount of fuel.