I have 17" rims. I think they make the car. If you like the sport look go with the 17" rims. If the stock look is for you stay with the 15" rims. If I could I would get a chromed set like Vintage had on their show car. There is no better look. The balance is tough on 17" wheels but if you are looking for a smooth ride buy a different car. The differance in ride from 15 to 17 can't be much. options for 17" is much better for tires. Get what you want and don't cheap out. Rims make the car. You'll regret it later if you don't.
Check out
http://www.tirerack.com. Sumitomo HTRZ 315/35/17 ZR (Not drag radials) Testing these out.
tom