What’s the least formal thing I can wear to a black-tie event?
“Creative Black Tie” can be interpreted as a “tuxedo combined with whimsical items such as bow tie and cummerbund.” However in the wrong hands this can easily become a gimmick; so avoid a pad lock and chain around your neck, a la Sid Vicious in his "My Way" video.
Instead, try my Bowie by Keanan Duffty Gray tuxedo shirt with the lyrics from "Let's Dance" screen printed across the front. Wear it with a leather tie and a two button, single-breasted black suit. It's a more rock ‘n’ roll alternative and it's a 'cheap chic' ensemble that will impress everyone. You'll be dressy without having to wear a regular tux.
When is it time to retire clothes? Jeans? Shoes? Jackets? Dress shirts?
If it's a timeless classic, wear it until it falls apart. If it's something you really love, or paid a lot for, learn how to maintain it properly. Many English gentlemen have learned this lesson, and a big part of their style is a beautifully worn-in, impeccable garment or accessory. If it's a trendy item, retire it when you see any pop star wearing it. You should look like a leader, not a follower.