We've only got the one run of cat5 going along the stairs. And some coax that's now redundant since we ditched the TV licence. There are about 4 runs of it going through a cunning gap where the floorboard split, along beside the heating pipes and down through the cupboard under the stairs, thobut. Only one actually carries ethernet, though (there's a switch and ATA in the cupboard to feed the downstairs stuff). The rest is all serial buses, and the incoming line from BT must be in there somewhere.
As long as they're not a tripping hazard, we refuse to get upset about the presence of wires. That's the sort of wooly aesthetic thinking that leads to storing your bikes outside.
In the unlikely event of ever actually owning a house, I will of course fill the walls with UTP and/or conduit.