How can I setup a preview theme section?

I am curious the best way to setup theme demos for a Wordpress Network. I saw themeswitcher, but I am not sure it will do what I want.

Here is what I would like:
• Setup a subsite with general content and have the ability to assign different themes on it.
• Setup a landing page with thumbnails of each theme
• Setup links to go to the subsite with the theme assigned to it.

Or...

am I better off using site cloner and setup a separate subsite for each theme? I kind of like how woothemes has theirs setup:

https://www.woothemes.com/product-category/themes/

Anyway, I want to ultimately create live demos of themes we want to offer. I would prefer one subsite with standard content rather than multiple subsites if its possible, but I don't want menus to reset, etc. etc.