14 gauge , but if you must 12 gauge -Yes, Monoprice is very good.
Wire is wire. You cannot alter the laws of physics and electronics. The copper is the same; there are differences in the visual athetics, structure quality and the connector quality. Thier is eletrical shielding and dielectrics, but in atcual reality and audio aaccuity there is very little discenrable effect, except in the mind's ear

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For almost all speaker runs 14 gauge is sufficient ( obviously you should use 12 gauage for longet runs, e.g. 50ft).
Many people over spec their speaker wire, 12 gauge is fine, but when you start going 10 gauge and larger (even lower wire gauge number) you are being absurd!
Yes, Monoprice is a very good souce of quality inexpensive cables. Bluejeanscables is another good source, but a little more expensive.
You can buy more expnsive cables, but you exceed the economic point of diminishing return. For example, Pear Cable Company Anjou cable. ( I do not recommend paying this much!)
http://www.pearcable.com/sub_products_anjou_sc.htm
Many, many stores sell HT equipment at a good, very good and even sometimes a great price and the they try to make their money on extended warranties, usrge protectors, power distribution centers and connecting cables. Some especially push a type know as
"an imaginary creature usually having various human and animal parts
giant: someone or something that is abnormally large and powerful
freak: a person or animal that is markedly unusual or deformed
a cruel wicked and inhuman person
(medicine) a grossly malformed and usually nonviable fetus" Monoprice, Blue Jeans Cables are much.much better choices.
Banana plugs on the end of cables, make them easily to connect securely and also to make a very good electrical connection. Sometimes spade connections make secure connections, but I would not recommend them because they can come loose and made a poor eletrical connection or even worse completely disconnect if the tightening nut loosens up.
Here is a very appropriate article of wire gauge size and speaker wire cost/quality:
http://query.nytimes.com/gst/fullpage.html?res=9D06E1D61739F930A15751C1A96F958260
Good Luck and Wire Onward!
MidCow2