It seems like you're just interested in a wire-less audio connection, not something over wifi.
If so, this might work for you:
http://www.audioengineusa.com/w1_home.php
It has received good reviews for sound quality and ease of use. It basically is a pair of USB powered gizmos that stream stereo audio from one to the other. They use a 3.5" stereo jack. It's possible to have one source and a number of targets, although you can connect to only one target at a time. It seems like it would work pretty well on the Pandora end -- just plug it into the USB port and the audio port. On the target end, you can get a USB adapter and maybe a USB extension.
AFAIK, there is no wireless optical solution, except for maybe wireless HDMI, which is probably overkill and not very convenient on the Pandora end, unless you really want surround sound. (I don't even know if the Pandora is surround audio capable.)
This should give you better audio quality and/or better range than Bluetooth audio. However, I can't say for sure, since I don't own a set. I do own the company's speakers, which give surprisingly good audio quality for the price. In my experience, they're a good company.
Hope that helps.