OK, here’s the next revision of my new theme, partially based on the feedback that some of you provided.
I’ve always resisted going to 3 columns, but I think it works in this case. It was a bit tricky to do while keeping the underlying HTML source order the same (content first, then the two sidebars after it - for SEO purposes), but I think it will do for now.
I will probably still eventually go back and change that part, though, because there are some drawbacks with this approach. The main one is that you loose some of the sidebar content if you’re viewing it in a window narrower than about 1000px at the default text size.
The other is similar and related (due to the content column being centered), in that if you resize the text too large you will not be able to see the edges of the content column anymore, and you can’t scroll to see them. This one’s not as big of a deal, though, since the text is already large enough to start with and there’s still a bit of room to bump it up before running into that problem.