On My Mind: Cocktail Dresses

I have an upcoming event where I will be wearing a cocktail dress, and I have been scanning many online sights for some potential dresses. Here is what I found...
a very classic Carmen Marc Valvo with metallic tones
A simple and chic Parker dress with some sparkle
This classic number with a great back that is just asking for some great accessories
{bright shoes & pretty earrings}

This stunning winter blue one with gorgeous embellishment
along the sweetheart top... just beautiful!
Lastly... my favorite Shoshanna option! I love the metallic lace in this soft pink color. I just adore this dress. It is so perfectly girly and pretty. LOVE.

Any thoughts or opinions? Where do you find your favorite cocktail dresses?