I agree with
@Brett327 and a few others above. If your current phone is compatible with a GSM sim card, I would pick up a "carte sim prepayee" for $20ish at a wireless provider like SFR (
https://www.sfr.fr/telephonie-mobile/sfr-la-carte.html#) or Free (
http://mobile.free.fr/) after you arrive and can visit a store in town someplace. Then you can have waze which works fine in France, albeit with overly ambitious ETAs.
I think renting a car once you get there is a a good call, so long as you aren't staying overnight in a big city like Paris with it. Trains are generally excellent in France, and SNCF has a decent English user interface via the sncf app, or the oui sncf app. I would recommend the SNCF high speed train (TGV) for a trip to Lyon or anywhere further away. I think the SW of the country, the mountains, and the Normande/Bretagne area are all a little more fun with a car though. Hertz was always good to me there, and if you use that amex platinum many folks have, you can safely decline most if not all supplemental insurances. Most big city train stations have car rentals right there in the station.
I found Pointe de hoc, the airborne museum at sainte-mere-eglise, and the American cemetery to all be especially moving. I ate a piece of sole meuniere in Bayeux for dinner at a place called La Rapiere (stop it), washed it down with a local cider, and experienced something called the normand hole (stop it), all of which were splendid. If you have time and want to see le mont saint michel, that is another couple of hours SW, but very impressive. I would stay in Saint Malo for that, eat copious crepes, and read "All the light we cannot see," beforehand to set the scene for the whole trip. Have an excellent trip!