I have used a single column layout for the website (scotianaires.ca) which is a page-based site - lots of pages! However, I do have one blog page "Notices" which I've tried setting up with a right hand column that I can insert the Categories & Tags widgets so that as the number of posts becomes large, people can sort through the content more easily than scrolling down an endless page of entries. I modified the template in the Page Attribute panel - I can see the two column layout (with the widgets there) applied to the home page (which is a page not a post) when I click on "Preview Changes" but the two column layout does not appear on the page itself (http://scotianaires.ca/notices/).
This may be due to the fact that I've set up a "page" for the blog to display on - I have a static front page and in the Customize panel I've pointed the Posts page to Notices and the blog is definitely appearing.
But what I'd like is to have a blog "page" with the two column layout - how do I do that?