I'll jump on the ATC bandwagon. But also wonder if the dual squeezebox/Duet/Touch approach will be error proof. I have a Duet (one) and love it. But the idea that you will hook up a separate Touch to each speaker, via the built-in DAC and outputting only one channel and insuring the timing is going to be exact. . . I am not so sure how well that will work? Not saying it won't, but it would concern me that the tiniest timing difference would create huge problems.
Added to that, if you would be considering the ATC speakers, I really don't think you would want to be using the built-in DAC on the squeezebox.
Call in an electrician and my guess he can run a cable (speaker, interconnect or other) down through the floor and over to the other side of the fireplace to hide the cables. If you are going to do that, have him run all the cables you may have want to use so you are covered for the future.