As for media room I would get these things called brush plates, you can get nice looking ones that match your power sockets etc, rather than wiring speakers and HDMI cables and all sorts of other nonsense into the walls. Get a brush plate at the bottom and one about 1.5m up behind a wall mounted TV. That way you shouldn't notice cables and they should sit nice. I am running dual or triple Cat5e jackpoints to each TV with some extras in our room and the study. You can power a LOT of devices over Cat5/6 now, things like cameras, phones, wireless access points, so it is worthwhile and tidy to get extras.
So would you go wireless speakers for the sound?
That depends on a few things, I would cable in all my PC's appliances that can connect with minimal mess because it takes stress off the wifi. I would also buy good quality access points.
Personally if you get good quality wireless speakers like sonos play series then yeh they are nice because you can take them outside or put them in another room etc. But if you want to put speakers into your walls go for it. It is quite a bit more expensive. I have a Tivoli Audio Orb which I got for xmas, it goes pretty well, its not quite as mature as the Sonos product but it does sound good and it looks the part.