Speaker suggestions needed

[Grover]

I've got most of my system parts now except for the speakers, this is what I have:

 

Alpine CDA-9815 Headunit

Alpine CHA-S634 CD changer

Alpine SIR-ALP1 Sirius tuner

MTX Thunder6152 amp for the sub (bridged 4 Ohm 325W)

 

I also have a couple old amps from previous systems that I was going to reuse if possible to keep costs down.

 

Kenwood KAC-624 (40W x 2) for rear D-pillar speakers

Pioneer GM-X904 (Bridged 120-150W x 2) for front component speakers.

 

I have a '00 Yukon SLT and am looking to replace all the speakers including upgrading the sub to possibly a 10" if I can find a box to fit in the factory location.

 

Right now I have speakers in all 4 doors and in the rear D-pillars, should I replace them all or just the front doors?

 

I haven't really been into the car audio market for about 5 years so I'm not sure what's the best now.

 

I want to stay around the $300 range for each set of speakers (front doors, middle doors, and sub).

 

Let's hear your opinions.