1) For superchargers not on highways, I would want electric bike which you could either ride in place and watch an electricity gauge show how much you added back to the super charger battery or check it out and ride to anything within a reasonable radius.
2) I would want it to have a roof with solar panels and a gauge showing the percentage electricity consumed by the Supercharger generated by the solar panels and where the rest of electricity came from. Ideally there would be an interactive educational display for anyone interested.
3) There would be wifi hotspot so I could actually use the display to watch a movie or waste, I mean, enjoy countless hours spent obsessing on this forum. Maybe there could be an app that allowed me to message, communicate, play chess with other people at the supecharger. Or maybe there could be pieces of a story that you could only get from the specific super charger you were on, but these could be shared traded, or even altered ultimately forming a larger and larger picture of a multi layered mystery and hidden clues about upcoming Tesla reveals in them.
4) Of course the regular convenience stuff like 24hr toilet, great coffee and food, a valet to move the car along until the cars can do that for themselves, a detailer that would actually not scratch my paint and stuff like that.
5) One that had the battery swap setup Tesla once demoed
6) Tesla product samples like the new roof samples, home batteries, even a vending machine with Tesla stuff in it.
7) A hot tub etc,etc. There is a lot more I could imagine that would make a Super Charger stop great, but ...
8) probably the perfect super charger would be one that charged my car as fast or faster than filling the tank of an ice car and still be free.