i too use a cheap and light combination cable lock when I take a lock, which I may not always do. It is pretty minimal, but I find it acceptable.

Depending on where/how you tour will greatly affect what makes sense. I am mostly in rural small town settings for the large bulk of my touring. The few times I am in a higher risk setting I don't leave my bike out of sight my. In bigger cities I get a room and take the bike inside. If shopping in higher risk areas I take the bike in with me and wheel it up and down the aisles.