As a cyclist and a previous commercial motorist, I prefer a road with a single 12' lane with 8 ' of shoulder over two lane road with dual 10' lanes and no shoulder. This makes it safer for everyone, especially if there is an accident or a break down, I've found that wider lanes have better visibility and more wiggle room.

On the other hand, when its a multiple lane road, say 2 lanes or more in each direction, 12' lanes encourage speeding, as they are often similar to a highway in that respect. The speed difference between motorists and cyclists is a significant risk factor that needs to be taken into account on multiple lane roads.