I’m planning on a MINIMUM of 8,000 watts running, 10,000 watts surge power (for AC startup, load spikes etc.) and I might even go bigger – an 80% of my kitchen is propane!  [:p]
 
We had a large desert racing team for many years, and we found that you should only run at about 70% of your total genset capacity. So as an example, if I was burning 5,600 watts with everything turned on, I would need an 8,000 genset to have a good safety cushion. Nothing worse than popping breakers, having pistons cook, or turning off important appliances cuz you don’t have enough juice…
 
The important calculation here is how much do you need if EVERYTHING IS TURNED ON AT THE SAME TIME!
Then, give yourself an extra 20 to 30% more juice, and you won’t be short any time soon.
Dave