Gee. I guess I have shown my age. I was the bride, never a bridesmaid. I got married at 18, so I never participated in that sort of thing. Too late now. I would be one of the "older" invitees.
Just remember this one thing: all guys (yes, even us married ones) are thinking about one thing for the most part when we are interacting with women. It ain't pretty, but it's the truth.