Well, my backup system is pretty crude compared to all of the above. No massive generator, no massive fuel tank..........just a Listeroid 6 hp diesel belted to an 1800 rpm 2500 watt surplus generator. Hand start with a crank, mounted on a rolling frame that's stashed in a corner of the garage. It has a two gallon tank with a five gallon jerry can next to it. Power is transmitted through a heavy cord to a special outlet in the garage to the breaker panel outside. A manual lockout prevents the main breaker from being on any time the generator is in use to protect power company personnel. Pretty simple, huh?
During the horrible heat wave we had a couple of months back, the power went down. Normally not something really inconvenient, but when the evaporative cooler quit it got hot........really hot. I wheeled the beast out, swung the crank once and it started immediately. I was able to operate my cooler, refrigerator, freezer, a few lights and my tv set. I discovered later that all 2400 households in my little town were without power. The only places still "lit up" were City Hall, the Police Department, hospital and ME.
That's a feeling of security that's hard to beat.