Let's see...

For the last ten years I've had a Hogmanay do that's been black tie for about three of those ten.

Apart from that I've been to two black tie events - my own graduation ball for examen artium (marking the end of 13 years at school) and my ex boyfriend's graduation ball when he became BA (Hons).

Weddings are usually business suit or "summer dressy" (nobody gets married in winter), but one wedding I've been to was white tie or national costume. I was ten at the time, and wore my national costume with all the trimmings, as did everyone else. Don't think a single person wore white tie, though some of the women were in ball gowns.

I would keep the formal attire myself, but then I have a closet full of clothes I never wear, so my opinion might not count...