Saddle width depends on: sitbone width, and riding position. Usually touring is done in a more upright position, which requires a wider saddle vs. the same person in a sporty position.
The hole in the middle is for your crotch. If that bone hits hard plastic/metal, it hurts a lot, and you cannot ride more.
The B66 is a good choice for touring, probably it has already the right width and crotch "valley" for your body geometry.
See my post here for more on width: Brooks leather saddle break inBrooks leather saddle break in