Just to make this more interesting and eliminate all the duplicate answers, let's exclude the obvious: honeyfunds, B-lists, cash bars, registry cards in the invite, dollar dances, and an insufficient amount of food for the time of day/number of people.
Other than those big things that everyone here seems to agree are no-nos, what are your 3 (or more, if you're feeling ranty) top wedding pet peeves? Could be etiquette-related, style related (like if you're sick of burlap and mason jars), food related, music related, dress related...anything. What should those of us mid-planning avoid?