I looked at a 12kw generator, but after I did the math on operating costs, I opted for a 3000 watt Honda gasoline powered generator.

It can run:

2 refrigerator freezers
3 computers/networking equipment
several lights.
and our furnace.

This is more than enough for us. Best of all, it costs less than $20 a day to run.

When our power was out for almost two weeks, this would have been the result:

12kw generator = $7,500 in fuel
3000w generator = $280 in fuel

I'm glad I went the 3000 watt route. I do acknowledge that it is not as convenient as having an automatic cut-over, but since all of our appliances are corded, including the furnace, it really isn't that big of a deal to go on emergency power.