For what it's worth, Google Maps can pre-download the area you'll be in while on wifi, so even when away from cell towers it'll work seamlessly. You can do it manually, but also if your login notices that you have reservations (hotel, flight, etc), it'll actually RECOMMEND downloading the area map for where you are headed proactively.

I do have an old Garmin in the saddlebag of my Wing, and the Garmin Motorrad Navigator that came on my BMW R1200GSA, but on both I use the phone as a GPS near 100% of the time. Did a ~1000 mile trip last week and never missed a beat even with no signal for extended periods. YMMV.