Although I'm not really a bass player, just a musicians with access to some bass instruments... I'll throw this in.
From the viewpoint of what I like to hear... I like solo's in general to start with the melody, so as a listener I have a base point. Then make it 'bassier'. To me that means more rhythmic, not too many long tones. Then start deviating from the base melody ... double time.. altered rhythm... switch to minor and back... I guess the correct scales are involved, but as you add passing notes, blue notes, etc.. the line gets blurry... Anyway, that's what I like to hear. I'm still learning to walk.
From the viewpoint of what I like to hear... I like solo's in general to start with the melody, so as a listener I have a base point. Then make it 'bassier'. To me that means more rhythmic, not too many long tones. Then start deviating from the base melody ... double time.. altered rhythm... switch to minor and back... I guess the correct scales are involved, but as you add passing notes, blue notes, etc.. the line gets blurry... Anyway, that's what I like to hear. I'm still learning to walk.