Blog categorization and blog paths

Hello,

I've tried to sift thru the forums on this topic. I would like to categorize blogs and have each category set an appropriate blog url upon category selection. For instance, if a new blog was added with a category selection of 'Arts & Antiques' I'm hoping to set the blog path to something like http://www.primaryblog.com/arts-antiques/newblog. It seems likely that I would have to modify the blog_types plugin to do so but I just wanted to check on alternate solutions/approaches. I'm hoping to be able to list the blog categories hierarchically on the primary blog site.

In a related issue, when I try and set the site address directly in a newly added blog or editing the path of an existing blog to a path outside the root directory as above (www.primaryblog.com/arts-antiques/newblog) I can't access the dashboard. The url http://www.primaryblog.com/arts-antiques/newblog/wp-admin/ gives me a page not found error.

Thanks for your help!