You can do networking over the powerlines, but it is slower and more expensive than cat5, plus I would assume it introduces quite a bit of noise into the line. It's typically seen as a retrofit solution, not a new construction solution. Run Cat6 and RG6 and run a lot of it. Much cheaper now than when the walls are up.
You may want to get an AV integrator in to give you pricing on a proper pre-wire so you're not stuck later with no options. If pre-wired properly, you'll be able to do what ever you'd like hardware wise down the road.