Living in south east Florida, I have seen my share of power outages. The last was when Wilma came through. I lost power for 9 days. My 5500 watt Coleman genset was used about 8 hours per day to power the hot water heater, and refrigerator mostly. It used about 5 gallons per 8 hour run. My home does have a full auxillary load panel so I can switch over to genny power and operate virtually all of the electrical appliances in the house excepting the air conditioner and electric stove.
My experience has taught me an order of importance: 1, refrigerator, 2, refrigerator (yes its that important) 3, microwave, 3, hot water heater; 4, communication equipment, (TV, charging phones & other batteries, radios, computer); 5, fans; 6, lighting. Remember, at night, lighting is easy with lanterns etc.
After Wilma, I sold the 5500 and bought a 7500 Yamaha electric start. FAR quieter. The noise of inexpensive gennys is obnoxious to begin with. After 4 or 5 days, the noise is well beyond irritating. I cannot emphasize this enough!
My suggestion is to get the quietest genset you can find, at least 5500 watt output and preferably more. Electric start is nice, especially if the wife must start it or age / infirmity limits your ability to yank a rope (remember it is a 12 hp single cylinder engine and demands a FIRM yank to crank it.)
I store about 40 gallons of gasoline for the hurricane season in various manners. At the end of the season, I use the gas in the wifes car and replace it at the beginning of next hurricane season.
My genset is secured with case hardened steel chains / locks to eyebolts in concrete. (then & now) The owner is also armed.
My experience is that smaller gennys are better than none as are noisy ones. However if you wish to be self sufficient for a week or more, get yourself more and quieter power. One last suggestion, use high quality synthetic motor oil in the genny. They work hard and hot, you want them to last a long time.
Stay dry.
Roger