Where do tubes matter most???

Here's a question from a newbie:

Where do you get the most of that nice "tube sound"? Some say the ratio of importance of tubes in the pre-amp vs power amp is 75/25, others say it's really 50/50. Some say a good hybrid amp will get you most of the way there, others seem to be more all or nothing.

I see a lot of Hybrids with pre-amp tubes, but I never see any hybrids that have solid state preamp with a tube amplifler. I'm assuming this is because It's less expensive to drive inefficient speakers with a solid state amplifier, but do considerations of musicality and sound fit into this design?