Here comes a first look at how a dual page layout can work. I've seen that lots of atlases use both a horizontal and a vertical map orientation. It is the map and the list of places that are tilted, the rest of the map are kept identical to the other pages keeping the overall experience more coordinated. 

There will be 0.5 inches margin for side notes like the earlier tests I did and also 0.25 inch for bleed. Note that the map overlap is included in the margin and bleed, this helps bridge the page gap and reduce the overall size. It can also look great with a traditional bound print and also work well with a spiral binding.

Areas with lots of settlements the actual map area can be reduced to give more room for a larger list. 

I really like this configuration, what do you think?