I second that, I use 14 AWG wire. I think 12 AWG is overkill. Here's a table to give you an idea on ga vs. length of the wire. As you can see 14 AWG takes you pretty far even with a 4 ohm speaker:http://www.roger-russell.com/wire/wire.htm#wiretable
For the sub cable, I use a special cable that also has a ground connector which gets hooked up the to the sub's ground and the receiver's ground. Apparently it helps with hum noises, if any.
Here's the sub cable that Magnolia gave to me for a couple of bucks when I got the Def Tech's from them. It was "open box", used cable, but who cares, works fine:http://www.needledoctor.com/Audioque...bwoofer-Cables
I think paying a lot for cables is a rip-off, I can't tell the difference between a decent cable and a very expensive one. This sub cable I would not have paid retail for it ever, but as I said I got it for free (almost).
For the speakers, I think it's OK to get a very good set if you can afford them. These are probably the only components that don't need an upgrade, not much changes in the speaker world, as opposed to receivers, DVD players, etc. You can make use of them for 10-15 yrs. or even more.