Summer beach weekends are often at seaside towns steeped in preppy style, especially in the Northeast. But what if you're an urbanite just visiting for the weekend? How far do you need to go to fit in?

For Ian Murray, the 37-year-old co-founder and co-chief executive of apparel brand Vineyard Vines, the preppy look is all about attitude, "exuding a sense of comfort in your environment—you've been here before, you know the etiquette and you're having a good time. You're having fun but you're also confident...