Okay, I get what you are saying, but I would still take exception to 3 things you stated (above):
"Most" ... for "Convenience"? Not really ... I haven't used our convenient "home" supercharger in a year ... and we didn't have a choice on our road trip.
Thank you to
@Rocky_H for adding the clarification. As he said, the convenience of Supercharging on a trip is that you don't have to sit for hours at an L2 or destination charger that is not at a location you are already spending hours at already.
If you don't like the price of a Supercharger (as you said, it's 3X the cost of home charging), then use home charging. What? You can't because you're on a road trip and not near home? Now maybe the point I was trying to make becomes clearer.
$4.50? End of June - We saw gas prices as low as $4.70 on up to $5.99. I got 287 wH / mile. So, yes, better than ICE, but it is CLOSE, and really not much to brag about like we are able to do when talking home charging.
I guess I didn't realize the goal was to be able to brag!
L2 for each travel day? No. I specifically looked for hotels with L2 charging, and we were able to hit about 4 out of 14 nights - and it is not easy to plan on arriving 'empty', and chargers are never guaranteed. So not much benefit to 'free' hotel charging.
For sure not every place has charging, and you're correct: it's never guaranteed. And I suspect it's much harder to find in out of the way places like Montana, but here are the J1772 or Destination charger options along the route from PA to Vegas:
Admittedly, some of these are campgrounds (not sure how to easily separate out campgrounds from hotels in the "lodging" filter in Plugshare), but doesn't seem like there is a real shortage of options if you really wanted to take advantage of overnight L2 charging. I've found that I can usually call the hotel in question and ask if they can block off the charging station for me that they are usually happy to do so. I just stayed at a Hampton Inn that actually located their charging station in one of the most inconvenient parking spots in the whole property, so I think they have actually figured out how to prevent ICEing!
As for planning on arriving 'empty', if you find it hard to do that, you're probably doing something wrong. Even the car itself will do a reasonable job of letting you know when you can leave the preceding Supercharger to show up with 10% at your destination (the hotel). If you have a reasonably high level of confidence in the charger being available (check Plugshare checkins, and call the hotel directly) or have a backup plan in case it winds up not being available, then you should certainly be able to arrive at 10%.