I have to say, the black cowl neck dress is the new little black dress style of choice, at least around where I live.
I have never been a huge fan of cowl necks to begin with, but I have to say that when worn appropriately, they can be very flattering.
Though I still think that a sweater is better cowl neck style than a dress, a little sleeveless cowl neck dress can be a lifesaver if you are often transitioning between work and socializing, since all you have to do is add or remove a cardigan or wrap to move from work to social.
I would recommend against going with straight silk cowl necks unless you are very, very slim though -- I see a lot of my co workers wearing silk cowl neck blouses or dresses, and since silk has so little give, it just ends up looking too tight or just weird.
Anyway, that's my two cents worth on cowl necks...what do you all think about them?