URL structure preference - to slash or not to slash?

I'm using custom post types in WordPress 3.0 to manage 'courses' (or seminars, lectures, whatever term you'd prefer to have in mind).

Now for viewing a single 'course', the url structure is;

/course/course-name/

But for multiple courses开发者_如何学运维?

/courses/category/category-name/

Or...

/course-category/category-name/

Or something entirely different?

From an SEO prespective the least forward slashes the better. Every level (forward slash) you put means (usually) less importance to (some) search engines.

I'd recommend you to use Level-1 URLs like

www.example.com/course-marketing-the-best-practices

Or Level-2 as much.

Search engines put less weight on indexing pages above 2nd levels. For example, the URL (http://pohee.com/Level-1/Level-2/Level-3), pages in "Level-3" level receives less focus by search engine crawler. by Pohee

Search engine crawlers expect the important content to be found within the first two or three subfolders. by GetInPosition

Some resources:

• SEO Tips: Ideal Folder Level In Website Hierarchy
• SEO and Dynamic Websites - how do they fit together?

Why not just /courses/category-name/ ?

It is the course category after all.