Lots of info there, Sarah.
I just scanned it a bit but it was good to see T-Mobile recommended as a good backup service. We've used them since 2000 & have always been happy with them. Of course it helps that Kansas City & San Diego were 2 of their primary coverage targets years ago. It is true though that they don't have as wide-coverage as some of the others, but they've been great for us.
And for $15/month Gaby can call France as much as she wants & she was able to use their free data roaming when she was there - love it!