What is the best way to use your Xfinity mobile phone internationally?

I am going to be traveling to Europe later this year and want to know the best way to deal with my phone so I don't get a surprise bill for several hundred dollars.  I see there is a Global Travel Pass for $10 per day or a pay as you go.  I probably won't be using it that much, maybe just to call home a couple times or to call or text the other people that are with us.  If data is that expensive, I can probably go without it for much of the time and just use wifi at night at the hotel.  Is there a better option than what is offered here?   What about these international sim cards I see that look a lot cheaper?  What is the best route to go?