Rationality as wisdom could be a highly useful frame, one that I've been considering myself. If I could describe in layman's terms what it means to be wise, I'd define it as unbiased judgment, appropriately high levels of knowledge, an accurate model of the world, moral behaviour, and the ability to employ your cognitive skills to make decisions which do not result in avoidable mistakes. In fact, just not making mistakes, be they cognitive, philosophical / intellectual, behavioral, moral, affective, economic or whatever, seems to be a good approximation of the definition of wisdom, which of course comes back to our title mission of becoming Less Wrong.
The best part of this frame is that you could draw upon ideas about rationality of people from other times and cultures, since wisdom is a pretty universal concept, more so than LW-style rationality. Perhaps browse the Rationality Quotes thread and exemplify your points using the most-upvoted quotes from there.
I was recently reminded of two pieces of cached wisdom about wisdom itself.
First, that "Wisdom is not knowledge, but the application of knowledge."
And "The wise learn from others what the foolish learn from experience, or not at all."
Upon the mention of the first, I was immediately reminded of the essence of rationality, further expounded on by the second. My thoughts then jumped to the negative reactions I have become accustomed to from those who hear me refer frequently to "rationality." My salient dedication to the idea evoked in their minds such as to induce the intonation of all the cliched wisdom against the "cold" thinking of those with whom I had (in their minds) associated myself, the Spocks of the world.
And here was a potential alternative. I may be able to communicate to their minds more nearly what I mean by "rationality" by using the word "wisdom" in its place. I suspect the term will seem them more palatable, even noble.
And when I explain all those things which once led them to begrudgingly ration out a measure of respect for rationality, the result shall be rather to confirm in their minds the power, pleasure, and purpose of the pursuit of wisdom.
And so I intend to frame my purposes in that light. Here's hoping...