Hi. I think its time to replace the breaks in my 2009 Infiniti G37x. I was planning to replace just the front but it might be better to replace both.
I have bought front Wagner OEx Ceramic Disc break pads already and I would like to us them. Should I buy the same pads for rear breaks? What rotors do you recommend getting for (non-sporty) daily car use in Floridas hot humid weather?

 

Brakes, not breaks
Centric premium rotors are a good choice, rockauto.com has them for good prices.
I would get the same rear pads to match the new front set. And you have 320mm front rotor, be sure that is in the part description.
2009 INFINITI G37 3.7L V6 Rotor | RockAuto

 

You can play around with different brands and/or compositions between the front and rear to modify brake bias without changing the proportioning valve but that's something only serious autocrossers and track rats do. Not recommended for Joe Public.