FH and I announced our engagement this Christmas, and of course, we got the requisite deluge of advice, etc.
BG: Most of my family is a particular denomination, wheras FH and myself are another. It's not the sort of thing we advertise, as it's really not appropriate for family discussion. Also, I've known the location of my dream wedding since I was about 10, and when we discussed it as a couple, we decided it was an excellent idea.
My aunt M is a dear lady, but has the unfortunate tendency to assume everyone agrees with her. So, once we had settled down and were discussing wedding ideas, she said, "Well, Specific Church Building is so beautiful, of course you'll want to have the ceremony there."
I just smiled, picked up a piece of pecan divinity, and said, "What an interesting assumption." Having had a lot of practice with this aunt, my grandmother helped out by asking where we were considering, and that was that. It went very well!