It might be nice to use your US cell phone overseas but I have never done so, and tend to purchase a new cheap cell phone in destinations right at the airport on the way to the hotel. A few Euros and then fees for time and data get you online quick enough. You may actually need a new cell or a new SIM one for Switzerland and one for France, don't know. A local phone will also give you a fresh phone number to share out while you are travelling in country.

I have enjoyed travelling with a tablet device for email access and Skype conversations, a Surface which will connect via Wifi, no data plan necessary. Good also for playing music and movies that I take along, as US subscription services aren't generally accessible from overseas.