Zones
For most 7.1 receivers, setting up another "Zone" as they state in their manual essentially removes the rear firing center speakers or in some cases the "presentation" speakers in the front. In either case, you are basically reduced to a 5.1 system by doing so (some receivers allow you 7.1 AND a seperate zone when that zone is hooked up through the presentation speakers, a stereo connector or rca plugs to an amplifier or amplified speaker setup). Most people I know never use more than the 5.1 system, but something you should check out is whether or not the receiver can play two digital sources at once. The reason being is that some people use the second zone for another TV system where they want to watch DVDs, etc. but may not need the 5.1 system. However, many receivers state that they can only allocate an analog source to the second zone. If that is a concern for you, make sure to look into it.
Personally, if you're routing cable to setup a whole-house audio system, I would either use a dedicated system for that, a receiver with one or more amplifiers attached to be able to drive the speakers, or a networked system with self-powered speakers. There are literally hundreds of systems available. Its worth a look if that suits your needs.