NAV,
Cable routing depends on the specifics of your house and where you are placing your equipment.
You can go under the floor (unless it's concrete!) if that suits your speakers and equipment location. Or behind skirting boards. Or use flat cable and simply go under carpets if you like.
Your best bet is to have a think, and post your proposals, then I'm sure you will get some comments. It's a bit difficult to make suggestions otherwise.
Cheers,
MarkP