Here's some info on German SIM plans:
http://prepaid-data-sim-card.wikia.com/wiki/Germany
If you read that page, it seems the German government in particular has put up some barriers to foreigners buying SIM cards there. I know nothing at all about German SIM cards. I use the Dutch Vodafone SIM I bought on eBay last year when I go to Europe and it has worked great for me, but every country is different. I'd recommend the Dutch Vodafone SIM, but you need a few weeks to get it mailed to you from the Netherlands, so it's probably too late for you now.
But if you can get a SIM in Germany, you may or may not be able to use it in Switzerland, as Switzerland is in neither the EU nor in the EEA where the new EU roaming rules have been enforced. My Vodafone SIM supports roaming there (they aren't required to), but other vendors may not. At worst, you'll need to buy new SIM cards in Switzerland.
http://prepaid-data-sim-card.wikia.com/wiki/Switzerland
I would install some sort of VOIP app on all your phones, however, and make sure you are connected. I'm not sure what kind of issues you've had with Skype, but I've used it for years on phones and laptops and it has worked great for me. You can even make calls to phones with Skype, but to call phone numbers you need to buy credit ($10 at a time) and then pay a few cents per minute per call. I use Google Hangouts mostly - that is like Skype but also allows free calls to US phone numbers, even to landlines (add a +1 prefix to US numbers to call them from Europe). Many others uses WhatsApp, which is very popular in Europe if you are trying to contact locals without paying to call a phone number. You can install any or all of these now (and should) - at least install Hangouts (and Hangouts Dialer on the Android phone) and try them out. Sometimes you need to verify an existing mobile number (to prove to Google you actually have some service already) one time - so do that now, don't wait til you get to Europe.