EUREKA!... OMG!... and a "Crikey" for the frosting... it was just OVER-inflated tires all along. Bled the fronts down to 30 psi and the rears to 35 and was attacking all my former butt-clenchers (RR crossings, manhole covers, potholes, rumble strips) all the way to and from work--not a jiggle! A tiny bit mushier on the corners, but it's not a sports car, not with those huge sidewalls, right?
Mega-Thanks and Much Grass to all who responded, all GREAT and insightful suggestions which eventually solved this puzzler!
Fook Mi for putting blind trust in this formerly switched-on shop (*cough* M@d H@tt3r *cough*), after their founder/guru left (Ol' Chvck was like House MD on such issues, NEVER would've let it leave the shop like this...) ... Every muscle/exotic car in town had their custom exhaust made there, turbo plumbing, suspensions set-up, after-market/oversize wheel-tire-extender combos sorted out...
Anyway, very interested to hear if anyone else wants to run this simple experiment--i.e. pump up all 4 corners to 40.000 PSI, and drive around town, hitting the usual road imperfections.
I'm still going to scrutinize all 4 ball-joints, replace all 4 shocks, and bleed the power steering, but it would seem there's always some finite amount of "play" in the multi-axis assembly known as The Front End, and it relies on semi-squishy tires to DAMPEN induced impulses.
Moral of the story: READ the placard (both halves), BEE-lieve the placard, OBEY da placard!