We just got back from a fast-paced "family" trip to mostly France. All adults, wife and I, two daughters and sons-in-law, so probably not the typical "family vacation." We flew to/from Europe from L.A., barely making connections outbound and a cancellation/reschedule on return. ("Good Morning. We're sorry we've cancelled your flight. Click here to go "Manage My Booking" to get the rebooked flight information and lodging or dining options. " "Click Here" didn't)
Somewhat pre-trip I'd added an A7Rvi to my ff kit. So, no budget for the 20-200. I decided to not take a back-up body nor 4 lenses for the various different anticipated opportunities. One body, two lenses, 20-70/4 and 28-200. Ideally, my 14/4 and a 20-200 might have provided somewhat better range and eliminated much of the lens swapping.
Fast paced including several pre-scheduled events, "tastings," timed entries, guided tours, etc. So, one body one lens may be too little but too many bag items can be more to fuss with and carry and go unused but not un-carried. Pacing, family age and numbers, itinerary, etc., can all shape the gear choices. My lenses, especially the 28-200 edged into large enough to make a larger body suitable. Others may have lens choices and interests leading to smaller bodies or aps-c.