How to address place cards?

It depends on the formality of your wedding! However, the 2nd version you described is not correct. Its either the first or third option.

FH and I are probably going to go with first option. I'd prefer to go with the third one, but I just feel like it might be a little too informal for our venue. Like @annakay511 said, it definitely depends on the formality of your wedding!

We did John & Mary Smith. But as pp said it depends on the formality of your wedding. Don't stress about it, at the end of the day hardly anyone will notice such a small detail.

If it's place cards, wouldn't they be individual? i.e., John Smith on one, Mary Smith on another? Or Mr. John Smith and Mrs. Mary Smith if you're going more formal.

Place cards need to be individually named, escort cards can have couples (as long as you don' t need to know what meal belongs to which person, otherwise, they need to be separate). Formality of the event will dictate which of either #1 or #3 you use.

We are using escort cards. I typically say place cards because I've noticed that many people on here don't know what escort cards are!