Friend....
Before you go “whole house” decide what you really need when your power goes out.
Then find out what circuits they are on in your breaker box
Then have a new breaker box installed
Have those circuits moved to the new breaker box
Have a transfer switch installed in between the original breaker box and your new one. “Normal” would be connected to grid power, “Generator” would take power from your generator feed.
You may be surprised how little power you can get by with.
If you are going to go with Natural Gas - also know that in a true emergency, you may well lose Gas, and electricity.
I'm leaning toward the minimal route, my wife is leaning toward the whole-house route.
The biggest issue is the A/C... and dealing with it's startup surge. The building code around here is another issue... there are certain requirements, so we do either have to split some circuits off to a separate panel or use the "smart switches" that automatically switch loads in and out when things start up. Even with a 27KW unit a little of that will be needed.
We're getting quotes from the main local companies, and should have more info early next week. We're dealing with companies that also deliver propane and work out of fortified buildings that gear up properly before hurricanes.