I love my Pioneer Premier 6.5's up front. I would step it up from the 5.25s. Take a look at my sig if you're interested. They handle 60rms and from what I've been hearing, they are one of the best co-ax speakers around. Either powered off your HU or a small amp.
As for the rears, toss em. The music "stage" should be in front of you IMHO.