LBD's don't need to be strapless to be sexy. I love the beautiful design of this Deco Dress ($173 at Le Train Bleu) for it's subtle sunburst detailing, harking back to another time and era. Le Train Bleu is one of my favorite online sites to find beautiful vintage-style or modern dresses that you don't see everywhere else.
Here are more LBD picks from Le Train Bleu:
Dahl Dress ($63)
Noir Dress ($152)
Sophie Dress ($85)
Origami Dress ($98)