First, go play GTA4, but instead of using the excellent taxi based instant travel system, do nothing but drive cars... everywhere. I don't think you realize how tedious it is, it's really the same as driving cars in real life. By the end of that game I was taking taxis everywhere.
It may seem like an interesting thing to include, but it's really not needed. Perhaps the worst feature of GTA4 was the fact that you had to drive places.
And honestly, why drive cars when you can grind on power or rail lines? Or leap from the tops of buildings?
Also, why would you want to go into a store of a clinic? This game isn't a satire of America, it's not a life sim, it's not supposed to be GTA. Instead, it's a superhero origin story, and you don't really see them going into stores to pickup their superhero outfits.