I understand all you suggesting SONOS for a NEW multi room system yet the OP has all ready did all the leg work and has wired his house to a central location for multi-room audio.
Or, look at the APAD controllers that Tunksy31 recommended. To add insult to injury, to get this user interface from 1990, you need to run a bunch of additional wires in your walls!
Dances I concur with you that this is a 1990's design and personally dislike it but in some cases it is a good solution for more control without having to pay a lot more for a full out Crestron TP that requires hrs of programming to look something like this
. Although Sonos is a good solution for a lot of people I think the OP is looking for something a bit more advanced than what a Sonos system is able to offer. As well like the OP has stated he wants 12 independent zones and with the number of pieces needed for each zone from Sonos he is going to need a lot of space to locate this equipment. With majority of the other Multi-room systems he is in need of 2 amp units plus his sources. Cost wise I believe someone had quited me about $500 per zone for Sonos, multiply that by 12 he is around $6000 PLUS he still needs to purchase the ipad/iphone to control the system, where if he went with a multi-room system keypads are included with each system purchase and compared to Crestron he would be looking around the same price AS WELL has a much smaller area needed to store the equipment.
Woby, I understand where you are coming from with having to pay for someone to make changes to a system that you own.
I work for a Crestron dealer and I see both aspects of having to charge for the programming as well as having to pay for someone to program a system that the end user owns. Because we are a dealer we are required to get training on how to program and install their equipment which costs the company time for the employee to receive the training plus all the other expenses incorporated. On the flip side I see the customers point of view where they want to make minor changes to the system as they have added a new piece or changed a piece of equipment and now their system doesn't work until they pay for someone to make the change.
What some MFG Companies allow is for the dealer to supply the end user with the software needed to alter the program. Although you have to look into this as each company is different.
I didn't suggest Crestron just because I am a dealer but from using Control4 and talking with other companies in the industry majority of them dislike Control4 due to many reasons.
There is also Nexus Audio
(Canadian Company) and Sonance
for multi-room systems as well. Sonance's software is available from their website, Nexus used to program from the main unit but that was a couple years ago (haven't used it since)
If you were wanting a two or three room solution I would suggest a Sonos system as well due to cost and usability. Since you are wanting a 12 room solution I would highly recommend a Crestron Adagio System. their AES allows for 10 source inputs AM/FM/XM/Sirius/Internet Radio are all optional cards with each card using 2 of the 10 sources and 6 room outputs. You would need their zone extender (AAE) to power your other 6 zones. With full house control using an APAD/Touch panel interface (Most people have keypads in bedrooms and bathrooms and touch panels in Kitchens and living rooms). It also allows for iPod touch, iPhone, iPad and Computer interfaces allowing you full control of your system anywhere in the world!
There is an OOTB (out of the Box) program already loaded onto the unit and you are able to program the APAD/keypads from the from panel of the main unit. I suggest the APAD a you are looking for true feedback as to ipod (providing you use the Crestron idock) and sat radio (tuner cards). Once you get into the Touch panel, iphone/ipad, and computer interfaces a lot more programming is required.