Well, unless they've got your chipped key or a tow truck it's going to be a little hard to steal, but I understand what you mean.
If you want function without so much bling you can try to pick up a set of the 370Z forged aluminium wheels on the cheap from someone that went aftermarket and is looking to ditch their OEM wheels. I picked up a set of the forged aluminum wheels for summer wear in my 350Z for $600 a little over a year ago. Outside of some tire mounting marks and wear in the lug holes they look perfect. Lighter and stronger, what's not to like about forged alumium? Here are the optional sport wheels from the 370Z.
Then if you're into the shiny look you can try and find the OEM polished aluminum that were made by ALCOA (the other forged aluminum for the 370Z and the ones for the 350Z are made by Rays of Japan).
I don't like the polished look of the ALCOA set, but I think that the shape looks MUCH better. I'd end up getting them powder coated if I had them, unless I had a black car, then they'd look pretty good.