I love my "40". I never considered taking it for road trips, because we could always take my wife's car. I got all the appearance of the more expensive cars, with leather, wheels and the pano roof, but without the extra range and performance. I wouldn't have bought the car if it were 10k more, because I just can't justify the expense, especially not just so I can drive to SD once a year. However... now I'm thinking of how cool it would be to be able to road trip this savage beast. The prospect of driving my wife's Lexus for 6 hours haunts me and fills me with sorrow. Heading up to the mountains of AZ, running up the California coast, it all would be so nice with Supercharging. But really, it's going to be a stretch to do PHX-SD or PHX-LA or PHX-LV even with the 60. I believe the map of proposed superchargers has one in the West Valley, so you can top up before heading across the desert. But $13k for the upgrade? Probably not worth it, that's a lot of plane tickets.
I think you would be a perfect candidate for a battery swap to an 85 kWh pack for your annual trip and then return to your 40 kWh pack when you get home. I think most people could live with the 60 kWh pack for their daily needs and if they could swap to an 85 kWh on the way out of town for $60 they would be completely happy. I think this will be Tesla's battery model in the long run to get the entry cost down.