Being British, I have just chuckled quietly to myself reading this thread... cheap laughs, I know.
Seriously though, braces were originally designed to be worn under a waistcoat, so you would never see them. Didn't stop the Victorians from having very fancy ones (for their own satisfaction). It wasn't until the post-WW1 period that braces were more visible as waistcoats became less popular. These days so few people wear them that it's hard to say that there are hard and fast rules. Personally, I don't wear them to be visible, but I won't worry if I am wearing a pair of trousers with braces and no waistcoat and have to take my jacket off. I would just go with good quality and avoid wearing any kind of novelty braces.