I own an Electroncis company and in my experience, I could never hear the difference between 12 gauge "Moster" speaker wire and 12 gauge Generic Speaker wire. I highly highly doubt you will either. The more expensive wire might look nicer, have a thicker coating or be more flexible but will it sound better? Not in my opinion.
RCA's are a little different, you want to stay clear of the "dollar Store" brands. Use good quality RCA's.
Speaking of which, I am surprised that in this day and age, there isn't a better standard of connecting amps and decks than analog RCA cables. I have personally beening installing systems for 20 years. I would have though by now a CAT5 cable carrying a full digital signal from deck to the amp would be the standard.