Michael, thanks for some brilliant use cases!
I particularly like the single event (a flight) that requires more than one time zone to make sense. My diary is chock full of cases where it looks like a flight out somewhere takes 2 hours but coming back takes 11! (strong winds ;-) -- : Eric S Fraga (0xFFFCF67D), Emacs 25.0.50.1, Org release_8.3beta-1260-gcedef7
