One of those whole house generators seems to be a great thing to have. However the ones installed around me run off natural gas, and in Texas the natural gas supply got disrupted and therefore if you had a natural gas fueled whole house generator you would be staring from your dark cold house at a $8-10,000 DOA monument in your yard right now. If you were off the gas line network and using propane I guess you'd be OK.
I have a Yamaha generator that is similar in size to the one John showed, and had an electrician friend install a generator panel with a outside plug to use. My friend didn't recommend trying to run too much off that generator for fear of overloading it, so it only runs the circuit with the fridge, the one for my boiler, and the one for my sump pump. Good enough to help insure against my food going bad, heat stays on, and basement doesn't flood, but not enough to live in comfort. I had the setup done 7 or 8 years ago, and since then just used it once when a summer storm knocked out power for 10 or 11 hours, but after that the only power outage I had that lasted more than a hour or two, was a early heavy wet snow storm that knocked out the power, and when I got home it was already after dark and spending an hour digging out the snow enough to get the generator out of the garage and over to the location it needed to be to plug into the house was not something I was going to tackle, so I lived without power and heat until around 4 in the morning when they finally got it back on.