Getting New Rear Brakes...

Both my rear brake calipers are now sticking. Well one is sticking, the other one is jamed crooked. The back of the rotors look like a mountains valley, and the pads look like there glaciers. I'm pretty durned sure its time for new brakes...even tho the car stops perfectly straight even at 70mph. Everything is original at 130k, except for the pads of course. If I gotta replace everything, should i get bigger discs, better calipers, ect? Or should I stick with stock and just get slotted and drilled rotors? Maybe go SHO all the way around?....I only have the money to do the rear right now...and the fronts should be good for a while........What options do I have here?