I've loaded Waze, so I now have Waze, iMap and Google maps available. Waze does what I want to accomplish - just show the road I'm on plus upcoming intersections, streets, etc. (Yeah, I did manufacture several trips so I could try things out.) Waze stays "on" for the duration of the trips I've taken so far today while the other two turn off when the iPhone times out. Additionally, Waze has the least cluttered screen of the three.
So, thanks for responding and for your suggestions. With your help, I tried different things and found one that works for me. Still, I'm intrigued by HERE WeGo, so I'll give that a look soon.