My approach is a little different. I use a combination of prebuilt rooms and flat tiles with separate walls, similar to the arenas. I find that special rooms work well for throne rooms, treasure rooms, crypts, etc.;the whereas the sections of floor tiles work for hallways, open rooms and small "closets". This flexibilty allows me to use the outside walls of the prebuilt rooms as the walls of the hallways as weel without doubling the wall thickness. It also allows the hallways to be open for stretches so the arms and weapons are not bangingthe walls as much. In my opinion, it's the best of both worlds.