We live out in the country and have a propane tank for our heating and cooking. Would it make sense to go to our propane supplier for an electrical generator that can run off the main tank when the grid goes down?
You can get tri-fuel (gasoline/nat. gas/propane) conversion kits here. Take some time to hunt around the site...lots of info.
Set up my little McCulloch 5700W portable to run on either 20# cylinders or the 500gal house tank as well as gasoline.
http://www.propane-generators.com/
Power in my rural area is usually out for 1-2 days although I have seen two five day outages in 10 years. I just deal with extension cords...furnace, fridge, TV and lamp.