CocoonTech is the forum for this questions, if you have experience with X10, take a look at UPB.
If you are going from scratch, every switch gets a cat5 cable. Wire in your security sensors. Wire in snakeable conduit everywhere else. Especially on your exterior walls. You will want a cable chase that goes from the attic to the basement.
Plan ahead and wire everything you can, then use the z-wave to hit everything you forgot to.