Touring's a special case IMHO, as the security concerns of your bags begins to dominate the problem.
Touring is a special case, and my first question before responding was going to be "where are you touring?"
Cos the UK appears to be a special case with regards to bike theft. I'm very precious about my bike on tour, given that it's my only mode of transport and the whole trip will be fucked if it gets nicked. I insist on bringing it inside overnight if at all possible. This generally results in much hilarity from the locals. A real eye-opener was staying in a city-centre estate in Switzerland, the kind of place where in the UK you would have your bike nicked while you were actually on it, probably at knife-point. The locals left their (expensive) bikes outside locked with a cheap cable through the quick-release front wheel. European tourists will generally leave their bikes unlocked with panniers on while they wander round a tourist attraction for hours. No-one touches their stuff.
I really don't understand why the UK is so different. If you leave your bike outside overnight and it's really well locked up, someone will take your saddle, lights, even valves if they're removable. Even in the daytime if you're out of sight for ten minutes. A cantankerous old git once slashed both my tyres because he didn't like me locking my bike to street furniture near his house on a "tidy" street. Really, the UK has an odd psyche that sees bikes as fair game for theft and vandalism rather than someone's possessions.