I'm not sure what you consider "light weight" but for your reference, stock 6 spoke 16" from 00-04 ZX3 weighs 19.3 lbs. Hubcap on a steel wheel weighs 1 lb.
Mille Miglia MM11-3 17" which sells for $120 ea Tirerack weighs 17.5 lbs, so weight difference is quite negligible.
If you pick a wheel that's 2 lbs lighter, but you pickup a set of tires that each weighs 3 lbs more, you're not doing yourself any good in weight reduction. When choosing tire, you have to watch the weight as well as the width for that reason.. 225/45/17 weighs 3 lbs more than the same make model 215/40/17, so you take a step backward in unsprung weight reduction.
So wheels are definitely aesthetics thing more than performance. Tires have much more effect on cornering performance.