Egads, yes, i never distilled it so logically / ergonomically before in my thoughts, but now that i see your words, this really rings bells.
Whilst you & the past several other Manjaroos have been posting your collectively thoughtful & interesting responses, i've been doing what i foretold in my OP. So now my Lappy & Tower have had a panel switcheroo... Main [permanently visible] atop, with App Menu Bar [Windows can cover (& btw, how super delighted i was to discover this setting weeks ago when i replaced Cairo-Dock with this Bar... so cool that if not covered by a window then it's visible, then is covered by any encroaching window, but magically can be forced to temporarily reappear in such case with mouse; i love it more than my erstwhile AutoHide)] at bottom.
This did bring me a temporary "crisis" of indecision & stress though. My browser [Vivaldi-Snapshot] runs [/ran] with my hitherto preference of Tabs Bar at top, but now that my Plasma Main Panel is at top of screen, all its widgets & program icons etc are [/were] directly adjacent to Vivaldi's Tabs Bar. It was a riot of visual assault, & very stressful to use given the barrage of competing visual stimuli. I'd not anticipated this collateral damage simply from moving my Panel, but [silver lining] it prompted me to re-explore alternative Tabs Bar placements [Vivaldi rocks!!]. Down the bottom is really uncomfortable, given it then forces me to constantly move mouse between both top & bottom of screen. On the right-hand side, ie, as a column not row now, seems to be an excellent workaround, so i shall retain this whole Brave New World with my best Aldous efforts, for as long as i can, to force my eyes & hands to recalibrate to the new positions all these key elements now occupy.
Gawd Linux is cool.