This is fascinating. I went to a wedding in the US last year, also with a 'cocktail attire' dress code. I wore knee-length navy, with tasteful sparkles in it, from Roman Originals (ideal for my age, probably not ypurs, OP). Bride and groom were Ivy League, parents were high-flyers, yet I was more glam than about 75% of the guests! Mother of the bride wore what looked like a (very comfortable!) day dress in polyester, and I really felt I'd upstaged her!