The Audi S6 encompasses Audi's technologies, performance, and comfort wrapped in a sleek package.
I've owned the S8 and the S6, although not quite the comfort level, is extremely close. The seats tend to wrap around me and the controls are within a comfortable reach.
I can't say enough about the performance and ride quality. I rarely drive in comfort mode because dynamic mode releases the beast from the 4.0L twin turbo and if you got it why not use it?