A lot depends on the age of the house and how much decorating you intend to do!
I would also advise against a loft (unless it is designed as a living space. A cupboard under the stairs might be more suitable.
As for running cables, under floor boards is ideal, but involves pulling up the floor borads. Ideally run the cables in flexible (plastic) conduit if you think you might add more later (but better to plan ahead and install twicce as much as you think you might need.
hard miniature trunking can be used for surface cables, or you can chase out channels in the plaster and 9again using trunking) hide the wires that way.
Or you could remove skirting boards and run cables behind then in the gap between the plaster and the floor boards, and replace the skirting boards afterwards.
As a last resort,you could cable tack the cables to the top of the skirting borad - only really discrete for a singel cable though.
Finqally there are the temp or semi-permanent options - laying cables under the carpet round the edge of a room.
Which method(s) you use reallky depends on the time you are prepared to spend, and the layout and construction of the house.