Just went to a wedding last weekend which made me think.... ladies wearing hats to weddings. I think it looks classy. I don't like the big ones that are a bit whimsical and "out there" looking, but I think a style like a simple fascinator looks really nice. I've been to dozens of US weddings, and can't seem to remember anyone wearing a hat.
I talked to my mom about it and she said that "back in her day" all ladies wore hats to weddings, and to mass!