If ranch, you can always add it later on your own. of course, if there are finished areas in the basement of a ranch, you can't easily add later so you should do what you want to do now.
If a colonial or other two floor style home, atleast run both cable styles to the attic. From the attic, getting into any second floor wall is easy.
Remember, it is easier to do this now than later and how much is it actually going to add to the overall cost? Probably not much in hte grand scheme of things.