My first advise is to really plan ahead. Think about where you may want to place TV's in the future. A friend of mine was building and was only planning on running CAT6 everywhere with no coax because the internet company he was going to go with runs the TV signals over CAT5 or higher. I suggested he also run RG-6 coax everywhere he was putting the CAT6. It is a good thing he did that, because he found out later that he didn't have good enough speeds to his house to be able to have TV over the internet connection. He ended up going with satellite for his TV. Sometimes the expense is in the termination of the cabling. Run extra, but only terminate where you will be placing the items now. put a blank plate over the unterminated and have that done at a later date when needed. Also, if your builder will let you, run the wire yourself. There are plenty of sites that give directions and guidelines for doing this. CAT5 or 6 can be used for many multiple room systems. With this in mind, you can Google for some of the many options out there.

In my two-story house, I ran 3/4 ENT ("Smurf tube") in 3 locations in each room with the tubes ending in either the attic or basement. A 2" PVC conduit runs straight from attic to basement. My cost was materials only as I did the labor. With that, whatever one wants can be installed as time and budget permit.