i did a little work on rattles today:
i bought some felt circles (3/16" thick), cut them in half, stuck them together and wedged them under the A-pillar panel which i got access to by taking off the tweeter covers. interestingly, the driver's side one was the one with the most play initially, but the stacked pad made it very rigid and i'm pretty confident it won't rattle again. for the passenger side, which initially was tighter, it still had some play in the corner closest the passenger, so i wedged a thin strip of cardboard in there to lock it tight. the only problem is that the tweeter cover doesn't sit flush anymore...not a big deal if it gets rid of the sound, but we'll see how it goes in the coming week and if the sound is gone. i may still remove the cardboard to see if it's needed or to try something different as i would like to keep that part flush else that may be a new source of noise.
as for my knee airbag piece, i strained my neck (literally -- it didn't feel very good) to look behind it using a headlamp. i can see why there is tons of play in that piece. i'm not sure that's the cause of my intermittent rattle, but i stuck another felt pad in there to remove one direction of motion that was easy to do. interestingly enough, there was already one tiny piece of foam tape there to apparently protect against a rattle from that area.
my gut hunch though is that my creaking/rattle is coming from somewhere higher up and not accessible to my hand... but we'll see. there is a lot of room for experimentation here.
i still haven't tried removing my headrest from the passenger side to see if i can isolate it to that part, but i do feel good that i actually took some steps today to maybe improve the rattling situation.
i probably should get the steering column plastic fixed by the dealer at some point although i'm not in a hurry as i don't have a rattle there.
finally, i put some pressure on the top panel of the info display. it sounds like there is actually some sort of foam tape under there already, but not enough? it's not clear that there is any easy way to remove that unless there are some clips that one would need to carefully pry up on.