Force all Areas to use same Layout

You specify a layout using:

@{ Layout = "_Layout"; }

If you want to make this easier to change all at once. Perhaps you could just set it as a view bag variable and pass it in on the controller. To make it even easier you could create a base controller that the other controllers inherit from and have it assign the layout to the view bag there.

Not sure why routing would need to change or perhaps I am not understanding. Hope this helps :)