I'd like to make one page.... selecting all the blocks and settings of my preference. Then use that as a template for making other pages - which would have all the same blocks, and same content. Then I can just edit the core content in one or two blocks, give the page a different URI and now I have 2 pages from a single template.

This is primarily useful in the initial design of a site - to easily attain a unified appearance as users navigate from page to page. I would then have a navigation menu that would link to several custom pages that all look alike, but feature different content an HTML block (as an example).