Hi,
The URL rewriting should rewrite "Default.aspx?AreaID=0" to the first page URL of that AreaID
This would help index customized menus, allowing the user to change the first page of each website whenever he pleases, and the URL would always be correct. Not to mention that it would respect the specific URL the user may set for that website.
We use this a lot with language versions.
Best Regards,