[oneday]

Yes, 17s are lighter...but you should also consider what tires you plan to run in the long run. Are you going to stay with ST style tires, or are you going to go all in and hit the purple or yellow crack [I am shopping Conti GA scrubs right now]. There are a lot of 18 scrubs these days since that is what the E46/92 GA cars run [the 17s I am shopping are from a Miata, go figure]. I opted for the 8.5 because it made more since for street driving, 9s require more pulling and camber all around to fit--especially in the rear, where you need to run camber arms to fit ($$$$). While I agree that an 18 with short sidewall will provide marginally better turn in, I question how perceptible that would be on an otherwise stock suspension--the added spring rate of a stiffer sidewall will be negated by the soft spring/damper.

As an argument for going square: You can rotate tires left to right [directional tires be damned as that only matters in the wet] and front to rear and get considerably more life out of them.