Good questions and answers. As you can see there are many options. For me I find it helpful to do a couple things:

1) Pick one option an "Play" with it.
2) Train your ears to hear what a certain scale sounds like over a chord.
3) Determine how you want to sound with the ear training from #2.
4) Experiment with polyrhythms in your ideas. It's not just about note selection but also your rhythmic approach in your ideas.

There are no quick fixes for your question. Improvisation is a lifetime of experiences and even the best never reach a place where they don't want to do more.