Writing solos is like a playground… IF that playground romp were being recorded for posterity and your performance judged by thousands of people for years, so no pressure there.
Traditionally I have treated a solo as a texture change and an extension of that section of the song, as well as a transition to the following section. I usually try not to play anything TOO shreddy and self-indulgent because that has a tendency to detract from the music… so I would try to let the song dictate what the solo needs as opposed to the solo dictating the feel of that section of the song.
BUT… while with the Aletheian stuff, I try to work a lot of the fretboard gymnastics into the ‘rhythm’ parts so that the solos are just a more pronounced version of that, with the SOLAMORS stuff, the rhythms are not all ‘shifting-meter-arpeggio-based’ like the core of the Aletheian rhythms are, so they have less lateral-movement but more groove and depth so that they can allow more room for vocal/drum/keyboard arrangements and layers without sounding too ‘busy’ or ‘jarring’ for people that don’t listen to a lot of ‘prog’ stuff.
That being the case, I am stretching out more into a few flashier solos and pulling in elements that I have avoided in the past in order to broaden the palette of sounds to make the solo sections ‘stand on their own’ a bit more. So I have been trying to work in some things that I don’t normally do to make this different and interesting (minor pentatonic runs, whammy bar tricks, harmonic minor runs, maybe some wah pedal stuff and effects, etc), so it has posed some new and interesting problems and possibilities.
I have avoided those typical solo devices in the past because I wanted to have a unique voice. That was one of the reasons that I started playing in alternate tunings: I wanted to make it impossible for me to play the ‘blues licks’ and top-string harmonic minor sweeps and arpeggios that have become ingrained in our minds and techniques. For example: to me, minor pentatonic with aeolian (and chromatic) passing tones played with a jerkey/urgent feel screams Dimebag Darrell, Harmonic minor plus minor pentatonic screams Gus G/Randy Rhodes, and Lydian with whammy bar dips and wah screams Steve Vai, especially if you harp on that 4th…
BUT in combining those concepts, a solo that starts out with an urgent minor pentatonic part, goes into some Hendrix-sliding-octaves leading into a harmonic minor run that slides into a lowered 7th at the end to a dominant and then dissolves into an slow/ambient lydian pattern all in the course of a 30 second solo: THAT is different… and weird, and interesting AND is providing me with hours of amusement and frustration.
It has been fun, and I am sure I will fall on my face a few times as well as making some people say ‘what the crap was that nonsense’, but I think the results will at least be fun and interesting.