If you have all electric heat and no other source of heat in a winter outage you will need a LARGE generator. Electric heat is very inefficient, but I suspect being in WA you have very cheap electricity thanks to lots of hydro electric power.
Let me give you a comparison, I have a mid size mostly gas house (gas heat, gas stove) with city water,
I have several small generators, and a couple of larger ones, the smallest being a little 1,000 watt Honda inverter gasoline fueled unit for the barebones last ditch emergency to keep a couple of lights on, maybe a couple of fans, and run the fridge and chest freezer alternating one or the other every few hours.
For a bit more comfortable life in an emergency next up is one of my 3KW MEP-016 series generators (more like 4.5KW by civilian ratings), it will keep the furnace blower going in the winter or a couple of portable / window air conditioners in the summer (8,800 btu +12,000 btu), run the fridge and chest freezer, some lights, the tv, computer, and with minimal power management (turn off an air conditioner for the few minutes while they are running) I can also run the microwave, toaster, etc.
Up from there I have a MEP-002a 5KW generator (again more like 7KW civilian), this would allow a bit more life as normal, it would let me run the washing machine and the clothes dryer, as well as power the electric water heater (4500 watt) with most everything else turned off while the water heats up on about half a gallon per hour of diesel.
And a 10 KW MEP-003a would let me run my central air conditioner in the summer allowing basic life as normal with a bit over 1 gallon per hour of fuel use
By comparison my mother lives in a fairly large all electric house on the family farm about 20 miles away (around 4,000 sq ft heated, 4 electric water heaters, one is a small 20 gallon, 2.5 HP well pump, 3 central electric heaters, plus electric stove, oven, dryer, etc.) , she also does not like the idea of doing major load management and wants life that is somewhat normal while living on generator power, so I put a 33KW Kohler commercial diesel generator at her house (note there is a 1,500 gallon diesel tank 1/8 mile away from her house at the shed where the tractors are kept), even with this beast that consumes close to 3 gallons per hour of diesel at full load she still has some load management required for winter outages. Specifically she can only run 2 of the 3 central electric heaters (not a big issue as she does have 2 fire places), and has to place some limits on doing cooking and laundry at the same time, for summer outages (hurricane area), it is life as normal, all 3 central air conditioners, plus running the stove, oven , and hot water from all water heaters at once (which also causes the well pump to run) will just max out the 33KW generator.
I hope this gives you some idea of what you may need, and more importantly how wide of difference there can be between what one person needs and what another needs. So go check out the amp draw on the data plates of everything you want to run, then go back and do it with what you NEED to run, and decide a course of action. (note data plates are often worst case draw, real world may be a good bit less, but it is a starting point)
Ike
p.s. I generally suggest manual transfer switches, they are cheaper and there is nothing to go wrong, unlike an automatic switch where you may be without power, have a running generator and a transfer switch that refuses to transfer because it thinks the voltage is 1% out of tolerance .