I know how you feel. my family (my mom and sister, whom I live with) is pretty non-religous. they can even be anti-religious at times. But, they call themselves Christians.
when I am eating with them, I make a quick sigh of the cross on my forhead with my thunb, or make the sign with my eyes. (that is, when I'm faithful enough to remember too.
making the sign of the cross would be crossing the line. when I told her we do that, she said "But Trevor, Catholics do that!". With protestants, if you don't want to upset them, you can't be too "Catholic" as they are very opposed to nearly everything that resembles Catholicism. they even go so far as to call the Roman Cathollic Church the "whore of Babylon".
you could explain that you are Catholic in the full sence of the word, an Orthodox Christian, belonging to the One Holy Catholic and Apostalic Church, but that would just make them even more "PO'd"
if you know it will start a confrentation, and you don't (like myself) have the knowledge to back up everything we do (you'd have to consult your priest or your books), I say just use desgression.
I know that Baptists think we're idol worshippers, so don't start talking about that icon you just had written or anything like that...
you could, however, talk about the saints and some of their lives that are rather more up lifting. it seems by their literature, Protestants love anything or anyone who is "inspirational.
I wish you good luck!