I ussuallyusually use http://www.example.com/product/123/subpage/456http://www.example.com/product/123/subpage/456
. In my case, I've been better off using this kind of URL rather than URL'sURLs with parameters. It's your decision tough...
Also, using htaccess (if you're using apacheApache) you can get the rewriting of the pages quite easillyeasily.