My power has gone out for up to two and a half days sometimes. So I have a 6500 watt generator. I just use extension cords (12 ga. contractor) to connect what I want. I'm mainly concerned with the refrigerator and freezer.
Be aware that generators can provide "dirty electricity" and some electronic things may not work with this electricity.
I'm reading lately that some new furnaces (with electronic internal controls) are not working on generator power.
For the electronic stuff and furnaces, get what is called an "online UPS" with "pure sine wave". This will provide perfect electricity for picky electronic devices and furnaces.
Match the wattage of the generator and UPS to more than what all you want to plug in and have running at the same time.
Dirty electricity looks like the following...
(First picture is what it should look like.)
http://www.jkovach.net/projects/powerquality/
Google shopping "online UPS" "pure sine"
http://www.google.com/products?q="online+UPS"+"pure+sine"&btnG=Search+Products&hl=en&show=dd