I have just over 20K on my '04 and notice a lot more wear (scoring) on the front rotors than the rear. Yes, I know the fronts do the majority of braking.
I've heard from more than one source the rotors will generally only take one resurfacing before replacement.

My question is, would it be practical to replace all the pads with good quality ceramics and only replace the front rotors with upgrades (stock size of course) leaving the original rear rotors which still look new?

 

with 20K you have plenty of pads left on the rear. Unless you do track days you can leave rears as is.
I would replace/resurface front rotors AND pads only.
Also-visual impression can be deceiving. What matters is pad material and rotor thickness left. It all depends on driving style. I got my car at 37K km(23K miles) and front pads were gone, so I replaced rotors/pads.
My replacement rotors look like crap now, but they work just fine, with about 50% of pads left at 38K miles, but they saw some heavy track use.

 

i did, i replaced only my front rotors from http://www.racingbrake.com/Default.asp?Redirected=Y
btw its OEM replacement i got the drilled one.