Eh, modes again.
The "trick" about writing a guitar-sounding solo is to think in strings. That is, as a guitarist you're writing stuff that is playable on the strings. As an example, playing a succession of fourths is really hard to play because it comes down to either moving the same finger really fast from one string to the next, or trying to roll off the finger, but that often doesn't give you good separation of the notes.
So, you won't get many fourths in a guitar solo. In stark contrast, perfect fifths and minor sixths => guitarists love them. Makes it easy to finger.
Also very easy to play: Same note, over and over. Hard to play on piano, easiest thing in the world on guitar.
rumborak