I ended up getting Hankook RS3, version 2 tires. I stuck with stock wheels (17x9.5 F and 18x10.5 R) because i'm cheap . I shod them with 255/40/17 F and 285/35/18 R. I got an alignment done and went off to an event in Stockton at San Joaquin Fairgrounds this Saturday and Sunday. I ran 38psi F and 34psi R on Saturday and 35psi F and 30psi R on Sunday. I was looking out for rollover and got scrubbing on the tires close to but not quite at the little triangle/arrow on the sidewall of the tire. I think those are where you don't want to wear beyond. I think I'll run them at the lower pressures as I think I PAX'd better on the second day with the reduced pressure. I haven't seen the results posted online yet but my ballpark assesment is the lower pressures resulted in the faster PAX'd results.
The run group had ~25 cars, course was short (~43sec, 2 cars on course at a time) and the air temp was 85-90F with full sun. I didn't notice much difference in grip between the runs. The Hankook's grip didn't seem to vary too much across this temperature range from first to last run. I guess that means the V2's do get to heat quickly which was their design intent, from what I hear.
This is all on a stock 2003 C5 Z06 running AS.
Next year, or when I wear out these Hankooks, i'll try to find some magnesium C5 rears to run with a spacer on the front and then I can pack on bigger tires up front. But for now these are lots of fun!