Personally, I would opt for the long patch cable. :) You can get
surface-mount plastic channels for wires that stick to the walls with
double-sticky tape.  Throw two data cables in there and put a
surface-mount RJ45 bricks.  You'll have a secure network, cut down on
radio traffic, and it won't look too ugly.

It does sound like you should be fine with three USB wireless adaptors
at about $30 each, if you really don't want patch cables. :)

Chad