14/4 wire for speakers- good idea? Bad idea?

Is it Canare 'star quad'?

That stuff always worked well for big bar installs. Used to buy it by the roll....

It's not a bad idea.. 

What you'll find with cables is that the materials and geometry can make a big difference. 

So, there's a good possibility you'll hear differences using different cables. Whether or not it's an improvement depends on all the other parts of your system.

If you'd like to experiment somewhat cheaply, DIY is a great way to start without dropping loads of cash. Here's a good resource: http://www.image99.net/blog/files/be8de0c383c5434907610d6b55049e69-75.html

DIY is great for isolation as well. I use springs from Grainger under my components for isolation.

I use that for my surrounds, side and rear. I would use a larger gauge wire for the front speakers. Don't know how far they are positioned from your amp, So 12 or even 10 Ga.might be better.

I'm not a big believer in retarded-priced cables. I think many people dramatically overstate their influence and I think the point of diminishing returns on investment begins at about $100. Consequently, I make my own with decent wire and termination. The ones I'm using now are made from a bunch of 16g OFC I had laying around, paracord, heat shrink tubing, and some decent bananas. The wire got stuffed inside the gutted paracord. 6 wires got round braided into a cable. Silver solder attached the connectors. Black shrink tubing made it all look neat and tidy. 11.5g combined for each side of the cable moves plenty of current without the liability of big wire inductance. They sound good and look cool.