For me, drum solos are musical challenges in which I try to express myself as much as possible in a rhythmical, melodical and also harmonical way. My drum solos therefore usually have two important pillars. There is a theme (in most cases melodic) and there is a form through which the drum solo can grow into a kind of musical composition.
For those interested, Escher's form is as follows.
Sounds
Theme, open
Groove
Theme 6/8 → 3/4 → 12/8 → 4/4 →
Solo
Theme 4/4 → 12/8 → 3/4 → 6/8 →
Pre ending
Theme, open
Ending.