Hey Jeff, as Milton Berle would say, "nice to see you in men's clothing."
I'm skipping NAMM this year, too much to do, I really can't take the time away from things. Have fun.
Hey, you did wind up drawing my attention with this statement:
Me personally, I LOVE the sound of a B natural over Dm7 (iim7), it is the note that personifies Dorian. I can't see why that would be considered a weak choice if you consider the harmonic richness. Of course we need to know the chord tones, that goes without saying, but as a soloist, and particularly as a bass soloist - I think it's important to understand the texture created by every note when played against a given chord structure. The chord tones work, sure. I guess that technically makes them "strong" choices because they are being represented in the comping. But that way of thinking would make the root the "strongest" choice. While performing my job of bass player, naturally I use the root all the time, but as a soloist - I try to find more compelling choices. The B over Dm7 is one of them. I also like C over G7 - Miles beat that one to death, gives you that sus4 vibe. I admit that F over CMaj7 is rough, I don't suggest it, but I do recommend that people try it so they know how it reacts. If you understand the texture, chances are you won't be drawn to use it unless you're film scoring a scene where a kitten is about to be mangled by farm equipment.
The key center approach also works great with modal jazz. When I play "So What".... I get awful tired just running up and down a Dm7 arpeggio or playing D Dorian. I play the entire key center, each mode, each chord structure, it makes it interesting.
Playing key centers is just one approach for improvising. It does "blanket" the chord structures, I call it "extrapolation", but that's semantics.
I don't recommend this approach to the exclusion of others, but it certainly does add a nice flavor. It will lead you to choices you might not hit if you're sticking close to the chord structure. Balance is a good thing. And I find that bass players in particular must break away from the "fundamentalist" approach toward harmony when they want to become melodic soloists.