Well, I’ve been doing some work on all of this and I am close to a workflow that I am happy with.
I have a group of KM macros now that handle moving the front window to the left or right 1/2 of the screen, centering on screen at the current window size, centering with a pre-set window size, centering in width but full height of the screen, making the window fill the full screen, moving to the left or right 1/3 or 2/3 of the screen or center 1/3 (useful when I have windows on the external 34" monitor I use at times with my MBP), and moving between screens.
Here is a picture of this macro group:
My big problem now is that I a) have not thought of a really good, coherent/consistent set of triggers that really makes sense to me, and b) remembering all of these things. I have tried just popping up a palette using the META key setup with Karabiner Elements, which works well, but is not the most facile approach, so I decided to hook in Alfred as well.
I now have an Alfred workflow (which I can share if anyone is interested) which when triggered queries KM to get all of the macros in this group and builds a selection list. I use the trigger “wc” (for window control) and it is pretty efficient to invoke Alfred, type WC, and either type some letters to narrow down the selection or just action the movement I want and have the window jump to its new location.
I suspect I will wind up creating keyboard shortcuts for the most common things I do after I have used this for a while to see what pops up as most commonly used, and leave the others to be selected only via palette or Alfred.