If you are going to this sort of trouble and also doing the adjacent bedrooms, have you considered putting Cat 5 (or similar) wiring in so that the wire socket can deliver any form of computer information, including music? Not necessarily the moustachian option, but it would enable your whole-house system to work off the music stored on a central computer.
Ah, I forgot about cat5. If you can find some really cheap (Everyone knows you have to run cat6 now! Otherwise, the horror!) it may be best to just run 2~3 lines to each room, you don't have to hook all of them up, and you can just use a pair of strands for the speakers from a single cable... good call!
I just recently ran some coax and cat5 to a few places in my house. My brother used to have a business doing websites and setting up networks for people about 10 years ago, and there was the cable end crimper, rj45 connectors, and two 'boxes' of cable just lying around. I only bought the multi-port faceplates and the the coax/rj45 inserts for them.
I actually didn't 'need' to use that ethernet cable, because I have another friend who also wired his house and had extra left over from his own 1000' spool and he was willing to sell it to me for half of what it cost him per foot (he considered it a sunk cost). You may be able to find some around on craigslist.