WebOffice 10.4 SP2 supports blending of caches in the WebOffice 10.4 SP2 clients, i.e. on the client side. This makes implementation and roll out of cached map services much easier.
Recommendation is to split up your map into basic "atomic" maps like
•zoning map,
•aerial image,
•hill shade map,
•survey map,
•cadastral map,
•etc.
each of the listed maps get organized as one MXD document.
Within a typical "atomic" map, layer visibility switching is not needed. Anyway being able to combine multiple "atomic" maps is essential.
By being able to combine multiple caches on the WebOffice 10.4 SP2 client side on basis of "atomic" maps, it gets really easy to roll out caches and at the same time remain very flexible concerning combination of multiple caches in whatever order and transparency level you want.

Multiple maps displayed on WebOffice 10.4 SP2 client side at same point of time - blended caches zoning and orthofoto