Please anyone correct me if I'm wrong, but I don't think you can combine reports on the same page in Books.
You can definitely combine them in a single Dashboard, although you might have to do a few trial & error attempts if your target is exporting it. I'd suggest experimenting with layouts Vertical Stack Panel, Wrap, and Grid (set 1 column and as many rows as you want cubeviews to be on the same page).
FTR, remember that you can also combine Dashboards, i.e. include a DB into another DB by nesting the related Embedded component - so you could have a Tab layout on the root dashboard, embedding other dashboards that each include multiple Cube Views with Vertical Stack Panel layouts.
