What the other guys said above plus my own 2c's... to get an 'emotional' sounding pice of lead out you real have to be 'feeling' the music. This is difficult to do and usually only comes after you've mastered the technical end of things. Try playing any lick robotically, get it exactly as it should be as per meter etc. Then, close your eyes and inject feeling into the same lick as you play it - no comparison - regarldess of the style (blues or shred etc), it will sound a lot different. If you break it down scientificaly it all comes down to minute subtleties in pinch harmonics, slides, bends an picking attack etc. It's a tough thing to do but once you are comfortable with the instrument you can 'let go' to a certain extent and stop thinking about where you're fingers are supposed go and what runs are coming next and you start playing with feel - this is when a solos start to get that emotional sound.
Hope that helps...