Traveling to Germany, Switzerland and Italy (SIM Cards)

If you're only going to be making occasional calls, have you considered roaming with your home network. That's probably the easiest and simplest solution, since you also plan to use Wi-Fi to send messages.

In the last few years my travel group has found the best option is to set up international roaming plan for the time you are away rather than purchase a local SIM card (one of the guys in my group manages mobile services for a Fortune 500 company so he REALLY did his research as a point of pride). But really this is just for emergency calls as you can set up your phone to do almost everything you need over wifi.

Here is what we did to get our phones ready:
Set up Google Voice (or Skype) to make calls using wifi.
Download offline maps (Google Maps on android even allows for driving directions offline).

To keep from using up cellular data you'll need to turn off data roaming when you are out and about.

For many years we did use local SIM cards but we have found them to be hit or miss on how well they worked. Sometimes the seemed to work in the store then nothing as soon as you leave the airport and no one really wants to troubleshoot tech issues while on vacation. The cost of one month roaming plans has dropped enough and the availability of wifi or offline services was enough to make the local SIM obsolete.

DJ

Many thanks for the guidance and information. Much appreciated.