I think the KISS principle should apply. At least while traveling with the others.Perhaps too simplified, but is this "their" trip or "your" photo shoot? I'd think either the 24-240 or 28-200 and a wide to supplement. Either should be plenty good enough. Go crazy with perfect gear after they are off on their cruise.
(note that I really like my 28-200 for travel, and 24 is somewhat better for wides, I do find some situations where there's a lot of switching needed at the 28mm point. Neither the 24-240 nor 28-200 solve that, just they avoid the swapping to go past 70mm, too.)
Thanks to the suggestions from all of you here, I made a couple of purchases toward making my final decision on which combo would be best for me for travel.
Here's a link to some images I took of the setups side by side:
