BiggD I cheated and went for the Honda 2000 by way of eliminating the heavy draw items in my house:
1 Gas cooktop vs electric
2 rinnai direct vent + wood stove - - [(if powering this directly just note, some heating units don't work with an un-bonded neutral (as found on suitcase gens)]
3 12v marine/rv water pump / 1 gal expansion tank with psi switch and 50 gal reservoir for toilets and a short shower use when power is out
4 LP clothes dryer
5 LP water heater
6 led lighting throughout the house
7 if you need a sump pump, u can use a 12v bilge pump rather than hoping a small generator will power the 110v primary pump during outages
I manufactured custom interlock plate to fit my panel. (that was a pain, but trial and error on cardboard before cutting the plate helped a ton)
the honda 2000 gen is nice as it is very quiet and efficient . That said, I dont worry about extended run times. it hardly sips fuel.
if you can keep the demand down in the house with said appliances, all you realistically need is a small genny.
the 12 v water system is so simple, it just backfeeds into a spigot. 40-60psi is no problem.
larger generators are typically not avail in an inverter style, thus cannot idle down to match the load. Generally speaking, 3000 watts is the typical inverter style gen avail within reasonable price.
large 5k and up simply draw loads of fuel and sing along at a set 3250 'ish' RPM to meet the 60hz frequency. inverter gens on the other hand do not.
outside recep for gen, slide the plate...
or a powerwall full of 18650 lithium cells and a quality inverter
YES A qualified home electrician is a must if you are not sure.
I just wanted to add that there are ways around the need for a larger generator
i installed a battery device that emits a ridiculously loud alarm when the power comes on. it just works by induction. amazon part. there is a pic up there by a poster. they do work well.
sorry for the long wind and gettin off topic slightly. oops