As others have described above, I find tube to offer sound with better texture, saturated harmonics and a presentation that seems to bloom naturally into the listening space. I think good solid state can sound smooth, natural and lacking in artificial edginess, but, I tend to find something missing that makes the sound seem flat and less engaging. I own a pretty decent solid state linestage (Levinson No. 32) but, I prefer my custom-built tube linestage (310 tube).
While you may get a "taste" of tube sound with a tube linestage, I think the electronic component that has the biggest impact is the amplifier. The right tube amplifier will make a huge difference (the wrong one likewise will sound quite bad). It is harder to find the amp that will mate well with a particular speaker than it is to match any other components, but, that is, to me, the big step in improving one's system.