After hearing horror stories about the Netherlands and theft, I always parked the bikes where we could see them from whatever place we were at. In a week of watching bikes, not a single person took the slightest bit of interest in them or the panniers.

I tend to view bike theft as more of a "right place, right time" thing. Can happen anywhere at anytime, but still rather unlikely to happen. I've made do with a cheap cable lock, I think keeping someone from picking it up and riding away at will takes care of all but the last 2% or so of theft.

Also keep in mind if you are somewhere where bike theft is a problem, there is probably a bike shop, you can always buy a locally-necessitated lock if conditions change.