A couple of things to consider:
1. If you (anyone) want to do multi room audio and video to any more than 2 separate rooms and be able to select sources independently then a proper multi-room system (1 or more devices) is required (as opposed to trying to do it with your AV Receiver and some distribution/switch box(es)). How sofisticated the multi-room system will determine how much control and ease you have operating the system.
2. HDMI, despite it's benefits, is still a flawed technology and really wasn't thought out that well. Not only does it give serious cause for concern when running it over longer lengths, it also loves playing 'funny buggers' with all of the required hand-shaking and sync'ing and other BS it needs to work. As an example to this, one of the oldest and biggest Multi-Room/whole-house equipment manufacturers - Elan Home Systems in the U.S. still don't offer a HDMI solution (and their stuff gets used in $1M house fitouts). What's the point of having the top technology if the user experience sucks?
Component Video can display up to 1080i (quite sure it can't do 1080p), but at least as an analogue technology it is much simpler and can run over long lengths with no issues.
eg. Elan's solution is this:
http://www.elanhomesystems.com/productdetail.asp?id=16
... plus this for the Component Video:
http://www.elanhomesystems.com/productdetail.asp?id=177
It connects to and powers it's own keypads (different types of keypads from about $450 to $4000 each...) via a single run of Cat5E. It's a very neat system and one of the easiest to use once installed.
Just another option...