I like using a dedicated GPS unit that gives audible cues for turns. It replaces a bike computer since it automatically records distance, speed and altitude (I don't even have to jot these down and reset the computer daily), and allows me to enjoy the scenery or concentrate on road safety without having to constantly glance down at a map or be preoccupied with wayfinding. It also gives me the freedom of taking any interesting detours with its ability to automatically reroute me back on track further on.
I toured with paper maps throughout Europe and North America in the 1990s and early 2000s and I much prefer the simplicity of something like a Garmin eTrex on my handlebar now.
You can get audible cues with Google maps but it runs your phone down in no time. I like sound of the Garmin eTrex. Does the it last all day, 8 hours say? Can you recharge it with one of those battery pack thingys if you're not near a power source?