Yes, black suits are perfectly appropriate for men at formal and semi-formal weddings
Try Rent the Runway or Little Borrowed Dress, which also have tons of silhouettes in coordinating colors ( Rent the Runway has loads of sequin gowns!) My advice would be to pick a few of the dresses you like from here, and ask your bridesmaids to pick one from the images above, or give them a store, designer, or fabric to choose from
Cassells Household Guide , which billed itself as an encyclopedia of domestic and social economy, summed up the problem like this, circa 1880: As a general rule, ladies do not like to see their maids dressed in the clothes they themselves have wornthe difference in the social scale of mistress and maid renders this unpleasing. But Cassells made one exception: a black or a dark-colored silk. Previously, a simple black dress meant a wealthy woman was dressing down. But by the 19th century, the black dress had become a staple of the lower and middle classes
Using Greek yogurt instead of mostly mayo or sour cream makes this version higher in protein and lighter while still keeping that creamy, tangy texture people love