I love Revolution and Mimbo for exactly the reasons you mention - they're not goofy and bloggy looking.
the way I see it, there's so many of us now using WP as a basic cms for our websites that designers should take that as an opportunity to create magazine/media looking designs. for the same dividends as the free bloggy templates - fame, prestige and eventually paying work.
If they're going to charge you for a design they better damned well provide adequate documentation and supporting material. What currently makes certain themes "best" is exactly that - they're stable and they have loads of documentation. Like, anything by Andreas Viklund (sp?) for example - this is why I love K2 (although I'm sort of getting tired of it as a design).