all brooks saddles are great for touring. the difference between the b66 and the b17 is that the b66 is a lot wider and is appropriate for a more upright position. The b17 is more of a standard width saddle for a bike set up with drop bars.

so if youre running an upright bar or you have the bars set above the height of your seat, the b66 is a good choice. if youre running drop bars below the saddle then you will be more comfortable on a b17