If the men in your bridal party prefer to wear suits, instead of choosing an outfit that clashes with your theme, they can wear the same outfit as the groomsmen or your fiance's wedding party. Depending on the aesthetic or style of the wedding, the bridesmen can wear a tie, brooch, or pocket square that correlates with what the other bridesmaids are wearing. Although the custom of wearing a corsage and boutonniere at a wedding is typically relegated to close family members, you can switch up the tradition to be solely for your bridal party to signify the people that are a part of your crew.
Another option is for your bridesmen to get a custom-tailored suit of the same color that the rest of the bridal party will wear. In order for them to not stick out too much, consider allowing all of your bridesmaids to don different styles in the same color. Not only will your bridesmen feel more comfortable because they don't look totally different, but the rest of the party can showcase their own individual style. Pick styles together so they can have their freedom, but you can also keep everything on brand.