I run a portable 5000 watt that I bought used for $275 after the big ice storm 3 or 4 years ago and a safety interlock on my original breaker panel. This is the least expensive way to make all the circuits in a house live. Off-the-grid living at my place is only slightly less convenient than on-the-grid. I made the interlock myself, but they are available commercially here:
http://www.interlockkit.com/.
I converted the used 5000 watt machine to electric start so my family can use it in my absence. I also created detailed instruction manuals for them, but it's really quite simple to operate and switch over.
Prior to owning the 5000 watt generator, I used a 4000 watt for 15 years and that was not quite powerful enough to run the well, furnace and fridge at the same time. The 5000 watt does so without any issues. Can't run an electric dryer on the 5000 watt, so we hang laundry when without power. The washer runs fine.