I would be afraid in a big natural disaster that the natural gas supply could be cut off too. Take for example a earthquake. The gas lines are going to break and when they do the gas is automatically shut off and then no more generator. Someone mentioned a tri fuel one that would be the cats meow because you would have 3 times the chance of finding some fuel somewhere.
My brother has a automatic transfer generator that runs on diesel fuel. But, for us on the farm that makes since because we have a lot of equipment that runs on diesel.