i went up to cape cod for a long weekend last month, and i tried to pack as little as humanly possible.  here is what made the final cut:

{from top center, clockwise:  billy reid men’s button down (also works as a beach coverup), j.crew pleated skirt (purchased for $20!), j.crew matchstick jeans (also $20), nike yoga capris and running shorts, 3 target cotton t-shirts, eres bathing suit, green anthropologie dress, gray isabel marant cardigan, 4 pairs of underwear, 2 sports bras, and 2 regular bras).  in the center is a pink equipment silk shirt.}

the clothes were chosen for their versatility and ability to make several outfits.  i.e. pink shirt + white skirt, black tee + white skirt, pink shirt + jeans + gray cardigan, etc.  one cotton shirt and the nike shorts/capris were used for sleeping, but could also double as activewear for outdoor activities.
i wore the superga flats on the way.  the beaded sandals were for any slightly dressier occasion, and the flip flops were restricted to the beach.