Natural Gas for fuel source is best option.
Big commercial ups setups use caterpillar for big generators.
Monthly tests are a given. Make a decision for partial power,. Make most lighting LED. Isolate some rooms for select power, clothes dryer for example. Once that amperage number is good, then consult with electrician on the additional panel, then decide on generators.
Make a test each season with total outage to gain confidence of the routine in worst conditions. Good luck
In my exposure, natural gas is best if you’re on a line, diesel if you’re not.