One of my favorite Spring outdoor activity is biking. No, not the intensive cycling type but the casual biking. If you're looking for a date idea or just something to do over the weekend I would recommend renting a bike to take promenade through the beach or the park. Since I live in California two of my favorite place is Griffith Park (Los Angeles) and Coronado Beach (San Diego). Again, California is pretty sunny so when I do bike I like to wear something light to let my skin breath (and look cute).
I normally wear linen shorts and light peasant top for casual biking. However, if you're going on a date, I would recommend wearing a chambray romper and accessorize with a pair of chandelier earrings and a floral pattern scarf (for unexpected weather change). Also, for comfortable biking, platform shoes or flat sandals are great choices.