First things first, don't bother with any type of rear speakers.
In my car I have 3 speakers (technically 5 if you include the tweeters). I have a set of components and a sub, all running off an amp, you don't need 6x9s, that's just chavtastic lol! OEM look is what it's all about, rear speakers will only take the sound away from the front which is where you want the sound stage to actually be.
The sound I get is phenomenal. I love it, the only thing I plan on doing is getting a better amp in the summer.