There is nothing new about a bride giving her guests a general guideline about how she would like them to dress for her wedding. The notation "Black tie" for a formal evening wedding is helpful, and it gives guests a clear idea of what type of attire will be appropriate. Some brides choose to go a lot further than that, however, requesting something very specific like "Formal beach attire" or "Black and white attire" (a la Kim Kardashian). This is a look at the ins and outs of dictating a dress code to your wedding guests.
One of the biggest headlines from Kim Kardashian's wedding was about guest Lindsay Lohan's revealing Marilyn Monroe inspired white dress. Lindsay's flowing white dress featured a big sparkly decoration and an abundance of cleavage, leading many to say that she appeared to be upstaging the bride. Kim's own mother wore a white Vera Wang dress with a big bow across the front, which looked for all the world like a wedding gown. And then there were the guests who were somberly attired in head to toe black. While insisting on a black and white dress code may have sounded like a good idea on paper, in reality it did not work out so well. Half of the guests looked like they were trying to steal the spotlight, while the other half did not look like they were attending a wedding on a sunny California day. This is the danger of the bride trying to exert too much control over what others wear!
As Kim Kardashian's wedding showed, it is better to give your wedding guests a general style guideline, rather than tell them exactly what to wear. It is not particularly fair to insist that people go out and buy a specific color dress to attend your wedding. What if someone showed up wearing the wrong color – would she be denied admission? Don't you trust your friends and family to choose attractive outfits and beautiful wedding jewelry? If your venue has specific requirements, such as all gentlemen must wear a jacket and tie, it would be entirely appropriate to pass along that information, but not such a great idea to tell them what color tie they have to wear!
The location of a wedding traditionally dictates what type of outfit is best. This is one of the funny things about notations like "Beach formal". Presumably the bride is worried that people will come wearing their shorts and flip flops if she does not say something. But really, anyone who knows anything about dressing for a wedding would know that flip flops or cut off shorts are never okay, and if they don't, the note on the invitation may not do much to help the situation. Besides, beaches generally are pretty informal places, and if you truly want a formal wedding, it might make more sense to choose a more formal venue.
If you do decide to give a dress code on your wedding invitations, it should be one that a) makes sense and b) is not a burden. Notations like "Creative semi-formal" do nothing but confuse people, while "Renaissance attire requested" is just plain unfair. Even if your wedding has a theme, it is not a costume party, and guests should not be required to rent a costume to attend. Examples of good dress code notations include things like "Dressy casual" or "Formal". They have a specific meaning and will help, rather than confuse, your guests when they go shopping for wedding jewelry and attire for your special occasion.