You've been offered a chance to have a custom preamp as well as custom tube monoblocks built to your spec. You enjoy a bit of tube flavor, but love tubes especially for the dimensionality and the life they tend to infuse into the sound. The gorgeous midrange and spacious highs don't hurt either! Ideally, at least a little punch can remain in the bass department. 15-20 watts per can be enough (leaving a little room for SET amps), but no initial bias towards any particular implementation. Bonus for using tubes that aren't exceedingly pricey or numerous, but still deliver the goods.
Now to the design. What tubes compliment do you gravitate towards and why? What circuit design do you utilize and why?