Besides bangs and pigtails, what are popular White females' hairstyles?
Bangs and pigtails are for children (and to be honest I see plenty of Asian girls with bangs and black girls with pigtails). But the "beach wave" look, which often involves weaves and hairpieces, seems to be popular with women of all races. The look though does usually require hair (either grown or purchased) that is of a typical Caucasian type. I don't think this is Kerry Washington's natural hair texture.
There are hundreds of hairstyles. Pigtails aren't popular for anyone older than about 7 years of age. Just Google hairstyles.