Brettski, Mom & Dad did exactly the same thing (auto switch and 20 kw gen set).
They were thinking they made a mistake because the surrounding people said that the power hardly ever goes out. It went out 3x this year so far, with the longest time being about 1/2 day. They are not regretting their decision now.
The genset runs on propane like the furnace and water heater. Auto start every week for a 15 minute run time. It's located about 100' from the main breaker panel in the house. We ran the wire in 2" plastic conduit to the house "just in case".