I have lived in an area with very frequent power outages for 13 years. Often we have a 3 or 4 day outage. Sometimes we are out for a couple of weeks. Life without power can be really miserable. Given a long outage, you will need heat, water, food, etc. At least in my area, when major outages occur, many times the roads are closed and businesses close. With profit pressures on local utilities, you can expect more frequent problems and longer duration events in the future.
Here is a place to look at possible solutions.
Although not cheap, I believe a whole house solution is the best. In addition to a generator (I think 20KW is about the right size for most modern houses), you will need a 200 amp transfer switch. The total cost will be around $10,000 plus installation. Peace of mind is expensive.
You will also need a voltage regulator for use on you system as all generators have problems maintaining constant voltage.