Ride quality - 17" or 18"

Any opinions on the difference in ride quality between 17" and 18" Sienas on an unlowered car?

I guess the 18"s would look better on a lowered car. Don't think I've ever seen the pre-facelift version on anything bigger than 17" though.

http://www.italiaspeed.com/new_model...166_index.html has a bunch of pictures of the facelift version on multispoke 18" wheels. These are available as replicas from http://www.performancealloys.com/ - no idea of how tough they are.