I am an electrician in the commercial field but I also do do wiring for VDV (voice-data-vidio) wiring. Much talk these days is about the "Smart House" that I think is realistically is still quite a few years away for the average home.
I would recommend that you wire any area that may use a TV, PC, fax, etc. for both Cat.5 cable for teledata and PC networking, RG-6 for cale TV and cable modem, also,if possible, run a 3/4" conduit sleeve either up or down to an accessible area to alow for any changes in wiring technology (fiber-optics included). As far as electrical circuits - if you have the capacity, try to establish where PC's, printers(especially laser printers) and keep these on there own dedicated circuits. Under no circumstances shoud you consider running multi-wire cables here as these electroninic devices create "harmonics" and also tend to overload the shared neutral conductor returning to the electrical panel.
I hope this information helps you cover all your bases for the forseeable future. Regard, Brian