The following link to AudioQuest's site shows their thoughts on cables in general and on bi-wiring.

http://www.audioquest.com/theory/cable_theory.html

I found it to be a pretty interesting read.

I recently bi-wired by Monitor Audio 5i's using the older hyperlitz version of the AudioQuest Slate. I purchased the wires and originally installed them in a normal single run configuration (non bi-wired). I then bought some good quality spades and converted them to an internal bi-wire. To be completely honest, I'm not sure if I hear any difference or not since I've changed them to bi-wire. (That should tell you something.) I did hear some positive differences when I changed to the better wires versus the cheap stuff that I have previously used. (wider and deep soundstage)

My guess is that if you didn't like the sound you got with the BetterCables in a single run, I doubt that you're going to like them as a bi-wire either. You might want to return what you've bought and try another brand or get some demo wires from a local dealer. Also, don't judge the wires too early. Supposedly, most better quality wires need to burn-in and may not sound good at all when originally connected, but, after running for a while, open up and smooth out. We're dealing with interactive systems and the wires that sound good to you in your system will be dependent on the components in your system and on your ears.

Personally, I think that wires can make a difference in the sound being reproduced. Before I'd jump into spending a considerable sum on some new bi-wire cables, I think that I'd install some decent quality interconnects (~$15-$25)and buy some moderately priced used speaker cables. I've heard bigger differences when replacing interconnects than I have speaker cable.(check out ebay and audiogon) If you don't like them, sell 'em to someone else and buy another pair.

Chris