I had Triumphs (750 Bonneville and 750 Trident) in Seattle when I went to UW a LONG time ago and I just left them outside the house uncovered since I didn't have a garage (or much else...) back then.
Here in seriously cold Maine I add plenty of Stabil and keep the tanks full. Years ago I had some rust in the tank of a bike that didn't have much gas in the tank over the winter so now I keep them full just to be sure. I keep them all (including ATVs) in the unheated garage and shed on battery tenders and don't start them until they go operational in the Spring. I keep the snowmobiles in their trailer on battery tenders and add Stabil during the off season.