I make frequent use of the voice command 'show superchargers' when I am on a trip. Makes it easy to see all superchargers to your destination, how busy they are, and usually lets me plan a couple different locations to charge as I start getting below 1/3 'tank'.
Charging is super fast at 20-50% so only takes a few minutes to add quite a bit of charge. Many/most superchargers are right off the highway so you don't lose hardly any time adding a little more charge and that way I always feel comfortable that I will reach my destination. Select 250kw chargers and you can add an extra hundred miles in the time it takes to check your emails.
As far as feeling unsafe at a supercharger, the only one that has ever creeped me out was Oakland, CA. Sketchy.