My generator gets run quite often throughout the year. I also use Lucas Ethanol Treatment with each tankful.
As for long periods of time, there are excellent products for keeping fuel fresh and fighting the negatives of ethanol. All my lawn care equipment is stored with StaBil. This week, I pulled out my aerators. They get used one month per year. At the end of the season last year, I filled each tank with fuel and StaBil. The first crank, they've taken no more than three pulls to start and run like the gas is brand new.