What about Sherlock Holmes? Once you get past his obvious shortcomings, he’s a pretty decent rationalist. Although he’s shown as sometimes being cold and distant, he has complex feelings and preferences (for instance, when he lets a thief go free, because he judges the guy is too scared to do it again). He’s not a caricature, such as Mr. Spock.
Well, at least that’ my view on the character...
Caledonian: Yeah, you’re right about what you said, but Holmes still represents an i/ideal/i of rationality, just like Spock, but he fits the role much better.
Kaj Sotala: I don’t recall that particular Holmes’ story, but Poe’s Auguste Dupin performs almost the same feat you described in “The Murders in the Rue Morgue” (and this kind of reasoning is mocked by Holmes in “A Study is Scarlet”, BTW).