This is interesting.
http://fivethirtyeight.com/features/when-does-praying-in-public-make-others-uncomfortable/
That’s more or less the results I would have expected, though prayer before meals bothered people slightly more than I would have thought.
Out of curiosity, would you feel uncomfortable if you were invited over for dinner and your hosts prayed grace? And if so, would it make you feel more at ease if they explained that they were going to pray grace, and you could pray or abstain from doing so as you wished?
Incidentally, the only person who has mentioned anything when I pray grace before lunch at school (silently, but visibly making the sign of the cross) was a kid from a Catholic family who obviously didn’t share his parents’ religious convictions and who teased me about it. I do go to a Catholic school, though, so even non-religious kids there probably wouldn’t think much of it (I got a ton of questions about it in elementary, though).